all|p  ©•  B.  Bill  Siihraru 

Nartli  (Earoltna  ^talr 


OH 


I 


This  book  was  presented  by 

MILTON  M.  LEONARD,  D.V.M. 

TO  THE 

VETERINARY  MEDICAL  LIBRARY 


This  book  is  due  on  the  date  indicated 
below  and  is  subject  to  an  overdue 
fine  as  posted  at  the  circulation  desk. 


EXCEPTION:  Date  due  will  be 
earlier  if  this  item  is  RECALLED. 


200M/06-99-991212 


PARASITES  AND  PARASITOSIS  OF  THE 
DOMESTIC  ANIMALS 


THE  MACMILLAN  COMPANY 


MACMILLAN  &  CO.,  Limited 


THE  MACMILLAN  CO.  OF  CANADA.  Ltd. 

TORONTO 


PARASITES   AND   PARASITOSIS 

OF  THE 

DOMESTIC  ANIMALS 


THE   ZOOLOGY   AND   CONTROL  OF   THE    ANIMAL 

PARASITES  AND  THE   PATHOGENESIS  AND 

TREATMENT  OF  PARASITIC  DISEASES 


BY 

B.  M.  UNDERHILL,  V.M.D. 

PROFESSOR  OF   PARASITOLOGY  AND   INSTRUCTOR  IN   ZOOLOGY  AND 
HISTOLOGY,    SCHOOL   OF    VETERINARY   MEDICINE,    UNIVER- 
SITY OF  PENNSYLVANIA,  ZOOLOGIST,  DIVISION  OF 
LABORATORIES,     PENNSYLVANIA    STATE 
BUREAU  OF  ANIMAL  INDUSTRY 


WITH  180  ILLUSTRATIONS 


THE  MACMILLAN  COMPANY 

1920 

All  rights  reserved 


COPYKIGHT,    1920 

By  the  MACMILLAN  COMPANY 


Set  up  and  printed.    Published  April.  1920 


PREFACE 

In  the  preparation  of  this  work  the  author  has  aimed  to  present 
clearh',  concisely,  and  in  orderly  manner  such  matter  pertaining  to  the 
subject  at  hand  as  seems  most  essential  to  the  needs  of  the  student  and 
the  practitioner.  Notwithstanding  its  elementary  character,  the  present 
rapid  advances  in  parasitology  have  necessitated  numerous  changes  and 
additions  to  the  manuscript  during  its  preparation.  New  species  and 
unsettling  facts  and  theories  as  to  some  which  are  not  new  are,  in  these 
days  of  intensive  research,  frequently  l^eing  brought  to  light  and  re- 
ported upon.  Some  of  these  findings  represent  or  lead  to  a  distinct 
advance  and,  though  the  observations  be  in  certain  cases  upon  obscure 
and  in  themselves  unimportant  species,  they  may,  by  analogy,  shed 
valuable  light  upon  life  histories  and  modes  of  infection  of  related  forms 
known  to  be  injurious  to  domestic  animals  and  man.  So  frequent  are 
these  steps  forward  that  it  might  almost  seem  better  to  leave  compara- 
tive parasitology  at  the  present  time  to  the  fragmental  attention  it  has 
mainly  received,  and  possibly  it  is  to  this  view  that  the  lack  of  a  recent 
American  volume  upon  the  subject  may  be  attributed.  Be  that  as  it 
may,  this  book  is  not  intended  to  be  comprehensive,  and  it  contains  but 
little  discussion,  historical  or  otherwise,  of  investigations  in  the  field  of 
medical  zoology, — limitations  which  ma.y,  in  measure,  contribute  to  it  a 
longer  period  of  usefulness  in  its  present  form  than  could  be  hoped  for 
in  an  exhaustive  treatise.  With  but  few  exceptions,  the  parasites  con- 
sidered are  those  most  likely  to  be  met  with  and  as  to  which  most  of  the 
facts  pertaining  to  their  biologv  and  pathogenicity  have  lieen  well 
established. 

The  treatment  of  the  subject  is  based  upon  the  advantages  of  pre- 
senting it  with  at  least  a  rudimental  attention  to  the  biologic  principles 
involved  in  parasitism,  a  knowledge  of  which  is  requisite  to  the  proper 
conception  of  parasitology  and  certainly  essential  to  intelligently 
applied  measures  of  control.  The  direct  and  lucid  style  of  the  text 
throughout  will,  it  is  hoped,  bring  these  briefly  considered  fundamentals 
before  the  reader  in  their  true  bearing  upon  the  whole  subject  and  render 
the  book  particularly  acceptalile  to  the  general  practitioner  as  well  as  to 
the  student. 

Teachers  will  appreciate  that  laboratory  work  should  supplement  the 
class-room  method  of  study.  Of  course  the  student  should  in  every 
case  see  the  parasite  under  consideration  in  so  far  as  this  is  possible. 
Methods  of  labomtor}"  technique  and  the  selection  of  type  specimens  for 


vi  PREFACE 

dissection  should,  in  the  author's  opinion,  be  left  to  the  teacher,  who 
should  certainly  be  the  one  best  qualified  to  fornnilatc  the  course  adapted 
to  his  needs.  No  general  outline,  therefore,  as  to  laljoratory  methods 
has  been  attempted. 

If,  as  has  been  said,  orighiality  is  not  the  best  reconnnendation  for  a 
work  of  this  kind,  the  author  feels  quite  sure  that  its  defects  cannot  to 
any  great  extent  be  attributed  to  that  source.  His  observations  in  the 
field  and  laboratory  have  been  utilized  in  the  preparation  of  the  book, 
but  contribute  nothing  to  its  pages  that  is  advanced  or  aggressively 
critical.  Excluding  the  first  three  chapters,  so  much  of  the  sul)ject- 
matter  has  been  drawn  from  the  published  results  of  the  labors  of  others 
that  the  numerous  sources  cannot  well  be  enumerated  here.  Acknowl- 
edgments are  especially  due  to  bulletins  and  articles  upon  various  topics 
of  parasitolog}'  written  by  workers  in  federal  and  state  bureaus  of  ex- 
perimental research.  Other  sources  which  have  been  relied  upon  and 
freely  used  are:  'M.  Neveu-Lemaire's  Parasitologic  des  Animaux  Domes- 
iiques;  Herms'  Medical  and  Veterinary  Entomology;  Riley  and  Johann- 
sen's  Handbook  of  Medical  Entomology;  Calkins'  Protozoology;  Neumann's 
Parasites  and  Parasitic  Diseases  of  the  Domesticated  Animals;  Bi-aun's 
Animal  Parasites  of  Man;  The  Journal  of  Parasitology;  The  American 
Edition  of  Hutyra  and  Marek,  and  Osborn's  Economic  Zoology. 

The  author  wishes  to  express  his  sincere  appreciation  and  thanks  to 
his  laboratory  coworker.  Dr.  Fred  Boerner,  Jr.,  for  his  assistance  in  the 
collection  of  specimens  and  in  the  examination  of  pathologic  material; 
also  to  Dr.  William  J.  Lentz  for  his  reading  and  valuable  criticism  of 
parts  of  the  manuscript,  and  to  Dr.  C.  P.  Fitch  for  his  helpful  suggestions 
as  to  sources  of  reference. 

Illustrations  for  a  work  of  this  character  will  ])e  an  aid  to  the  text  in 
proportion  as  they  are  exact  and  well  chosen.  For  the  study  of  mor- 
phologic characteristics  photographs  of  actual  specimens  are  often  too 
obscure  in  detail,  and  accurate  drawings  or  line  sketches  are,  as  a  rule,  of 
greater  service.  It  will  be  observed  that  man}'  of  the  figures  in  this 
book  are  taken  from  publications  issued  by  the  United  States  Depart- 
ment of  Agriculture.  Probably  no  better  drawings  of  these  subjects  have 
been  produced,  and  the  privilege  granted  to  use  them  is  esteemed  as  a 
helpful  favor  of  much  value  to  the  work.  In  this  connection  the  author 
would  especially  express  his  gratitude  to  Dr.  L.  0.  Howard.  Chief  of  the 
Bureau  of  Entomology,  to  Dr.  John  R.  ]\Iohler,  Chief  of  the  Bureau  of 
Animal  Industry,  to  Dr.  Herbert  Osborn,  to  Dr.  Howard  Crawley,  and 
to  Dr.  B.  H.  Ransom.  Finally,  thanks  are  due  to  Dr.  W.  H.  Hoedt  of 
Philadelphia,  for  his  skill  and  interest  in  preparing  the  photomicro- 
graphs and  many  of  the  drawings. 

B.   ]\I.   U. 

Philadelphia,  Pa. 


CONTENTS 

PART  I 

PRELIMINARY    CHAPTERS 
THE   EXTERNAL   PARASITES 

CHAPTER   I 

PAPE 

Introduction 1 

Origin  of  parasitism;  Influences  inhibiting  organic  multiplication;  The 
struggle  for  existence;  The  sheltered  mode  of  life;  Its  effect;  Phases  of  the 
symbiotic  relationship;  Example  of  mutualism;  Examples  of  commensalism ; 
True  parasitism;  Adaptive  and  degenerative  modifications  of  the  parasite; 
Faculties  of  parasitic  and  predatory  animals  compared;  Simplicity,  primitive 
and  degnerative;  The  Tunicata;  Functions  involved  in  adaptation  to  para- 
sitism; The  reproductive  process  in  MeJophagus  ovinus;  Development  oi  the 
reproductive  function  in  parasites;  Parasitism  of  Gaslrophilus  inteslinalis; 
Alternation  of  hosts  in  life  cycle  of  parasites;  The  complicated  cycle  of  the 
liver  fluke;  The  tapeworm  as  an  example  of  extreme  parasitism;  Deductions 
as  to  the  systematic  position  of  parasites  through  comparison  with  free-living 
forms. 

CHAPTER    II 

Forms  of  Parasitism  and  Influence  upon  the  Host 7 

Terms  used  in  parasitology;  Symbiosis;  Mutualism;  Commensalism; 
Helotism;  Parasitism;  Phytoparasites;  Zooparasites;  Optional  occasional 
parasites;  Obligate  occasional  parasites;  Determinate  transitory  parasites; 
Permanent  parasites;  Fixed  parasites;  Erratic  parasites;  Determinate 
erratic  parasites;  Monoxenous  parasites;  Heteroxenous  parasites;  Trans- 
migration; Incidental  or  stray  parasites;  Ectoparasites;  Entoparasites; 
Helminthes;  Terms  used  in  the  designation  of  parasitic  diseases;  Preda- 
cious and  parasitic  animals;  Factors  governing  injuiy  to  the  host  by  para- 
sites; General  etiologic  factors. 

CILIPTER   III 

Phulum  I.    Arthropoda 13 

Characteristics  of  the  Arthi'opoda;  Characteristics  of  the  class  Insecta; 
Insect  methods  of  reproduction;  Duration  of  life  of  insects. 


viii  CONTEXTS 

CHAPTER   I\- 

PAGE 

Mosquitoes  and  Gnats  ...     23 

Characteristics  of  tlic  order  Diptera;  Dipterous  iiarasitisni;  Charactis- 
tics  of  the  family  Culicida^;  Range  and  prevalence  of  mosquitoes;  Their 
breeding  habits;  Their  pathologic  importance;  Tlie  transmitter  of  malaria; 
Methods  of  distinguisliiug  between  Anopheles  and  Culex;  The  transmitter  of 
yellow  fever;  Characteristics  and  habits  of  the  species  Atles  caloirus;  Effect 
of  mosquitoes  upon  live  stock;  Mosquito  control;  Characteristics  of  the 
family  Simuliida;;  The  Southern  bufTalo  gnat;  Effect  of  its  attack  upon  live 
stock;  Control:  Protection  and  treatment. 

CHAl'TER   y 

The  Flies 35 

Characteristics  of  the  family  Tabanidse;  Horse-flies;  Gad-flies;  Effect  of 
their  attack;  Protection;  Characteristics  of  the  family  Muscida;  The 
house-fly;  Habits  of  the  house-fly  and  its  relation  to  the  transmission  of 
disease;  Its  control;  Protective  measures;  The  horn  fly;  Its  habits;  Effect  of 
its  attack;  Its  control;  The  tsetse  flies;  Characteristics  of  th£  genus  Glossina; 
Distribution  and  habits  of  tsetse  flies;  Their  relationship  to  trypanosomiasis; 
Investigations  by  Bruce  and  others;  Tsetse  fly  control;  Characteristics  of 
the  family  Hippoboscidaj;  The  "sheep  tick"  or  "louse  fly;"  Its  effect; 
Treatment. 

chapti:r  \T 

The  Dipterous  Larv.f, 50 

Myasis;  The  "screw  worm  fly;"  Its  habits;  Effect  of  its  attack;  Pro- 
tective measures;  Treatment;  The  flesh  flies;  The  blowfly;  Its  habits; 
Protective  measures;  Characteristics  of  the  family  CEstridae;  The  horse 
bot  flies;  Gastrophilus  inteslinnlls;  Its  habits  and  life  history;  Effect  of  the 
fly  and  larva)  upon  horses;  The  red-tailed  bot-fly;  Its  habits  and  effect;  The 
chin  fly;  The  ox  bot  or  warble  flies;  Tlunr  life  history;  Their  economic  im- 
portance; The  sheep  bot  fly;  Its  habits  and  life  history;  Effect  of  the  at- 
tack of  the  fly  and  its  larva>;  Protection  and  treatment. 

CHAPTER  VII 

The  Fleas 65 

Characteristics  of  the  order  Siphonaptera;  The  dog,  cat,  and  human  fleas; 
Differentiation  of  species;  Life  history;  Relation  of  fleas  to  the  transmis- 
sion of  infectious  diseases;  Treatment  and  control, 

CHAPTER    VIII 

The  Lice 70 

The  sucking  lice;  Characteristics  of  the  order  Siphunculata;  The  biting 
lice;  Characteristics  of  the  order  Mallophaga;  Pediculosis  of  domestic  ani- 


CONTENTS  ix 

PAGE 

mals  in  general;  Pediculosis  of  the  horse;  Pediculosis  of  cattle;  Pediculosis 
of  the  sheep  and  goat;  Pediculosis  of  the  hog;  Pediculosis  of  the  dog  and 
cat;  Pediculosis  of  man;  Control  and  treatment  of  pediculosis. 

CHAPTER  IX 

Lice  of  Poultry;  The  Bedbug 82 

Prevalence  and  effect  of  poultry  lice;  Species  infesting  chickens;  Species 
infesting  turkej-s;  Species  infesting  ducks  and  geese;  Species  infesting 
swan;  Species  infesting  pigeons;  Control  and  treatment  of  poultry  lice; 
Characteristics  of  the  order  Hemiptera;  Characteristics  of  the  family  Cimi- 
cida);  The  common  bedbug;  Its  habits  and  effect  of  its  bite;  The  bedbug  as 
a  pest  of  poultry;  Control. 

CHAPTER  X 

The  Mites 94 

Characteristics  of  the  class  Arachnida;  Characteristics  of  the  order  Acar- 
ina;  Parasitism  oi  the  Acarina;  Acariasis;  Characteristics  of  the  family  Ga- 
masidse;  The  gamasid  mites  of  poultry;  Habits  and  effect  of  their  attack; 
Control;  Characteristics  of  the  family  Trombidiidse ;  The  harvest  mites, 
chiggers,  or  red  bugs;  Habits  and  effect  of  their  attack;  Treatment;  The 
mange,  scab,  or  itch  mites;  Characteristics  of  the  family  Sarcoptidaj;  The 
genera  Sarcoptes;  Notoedrcs,  Otodectes,  Cnemidocoptes,  Laminosioptes, 
Cj'toleichus,  Psoroptes,  and  Chorioptes;  Their  respective  characteristics, 
hosts,  and  modes  of  attack;  Characteristics  of  the  family  Demodecidse; 
Mange  and  scabies  of  the  various  domestic  animals;  Sarcoptic  mange;  De- 
modectic  or  foUicular  mange;  Notoedric  or  head  mange  of  the  cat  and  rab- 
bit; Otodectic  or  auricular  mange;  Psoroptic  scabies;  Auricular  scabies  oi 
the  rabbit;  Chorioptic  or  leg  scabies;  Symptoms,  development,  lesions,  diag- 
nosis, and  transmission  of  mange  and  scabies. 

CHAPTER  XI 

Treatment  of  Mange  and  Scabies 120 

General  considerations;  Treatment  of  sarcoptic  mange  ot  the  horse;  Of 
the  dog;  Of  the  goat;  Of  the  sheep;  Of  cattle;  Treatment  of  notoedric  mange 
of  the  cat  and  rabbit;  Treatment  of  demodectic  mange;  Treatment  of  oto- 
dectic mange;  Treatment  of  psoroptic  scabies  of  the  sheep;  of  cattle;  Of 
the  horse;  Of  the  rabbit,  Treatment  of  chorioptic  scabies  of  the  horse;  Of 
cattle. 

CHAPTER  XII 

Mange  of  Poultry 132 

The  burrowing  mite  of  poultry-;  Leg  mange  or  "scaly  leg";  Its  course 
and  treatment;  The  depluming  mite;  The  deep-seated  acariases  of  birds;  The 
family  Cytoleichidse ;  The  connective  tissue  mite;  The  air  passage  mite. 


X  CONTENTS 

CHAPTER  XIII 

PAGE 

The  Ticks 136 

Structure  of  ticks  in  general;  Characteristics  of  the  superfamily  Ixo- 
doidea;  Characteristics  of  the  family  Argasidte;  The  fowl  tick;  Its  habits  and 
effect  upon  the  host;  Control;  The  spinose  ear  tick;  Its  habits  and  effect  upon 
the  host;  Treatment;  Characteristics  of  the  family  Ixodidse;  Description  of 
genera;  Species  found  upon  domestic  animals  in  the  United  States;  The 
Texas-fever  or  Southern  cattle  tick;  Biological  data  established  by  the  Zool- 
ogical Division  of  the  United  States  Bureau  of  Animal  Industry;  Life  his- 
tory of  the  Texas-fever  tick;  Its  nonparasitic  development;  Its  parasitic 
development;  Loss  occasioned  by  the  Texas-fever  tick;  Progress  made  in  its 
eradication;  The  order  Linguatulida;  Lingualula  rhinarin  of  the  nasal  cavi- 
ties of  mammals. 


PART  II 

THE  INTERNAL  PARASITES 
CHAPTER  XIV 

Phylum  II.    Platyhklminthes;  The  Flukes  and  Tapeworms 155 

Classification  of  the  parasitic  worms;  Characteristics  of  the  Platyhelm- 
inthes;  Characteristics  of  the  class  Trematoda;  The  liver  flukes;  Their  life 
history;  Prevalence  of  fascioliasis;  Infection;  Migration  of  flukes  within  the 
definitive  host  and  pathogenesis;  Fascioliasis  of  the  sheep;  Fascioliasis  of 
cattle;  Control  and  treatment;  The  blood  fluke;  Bilharziosis;  Characteristics 
of  the  class  Cestoda;  Characteristics  of  the  family  Tseniidfp;  Life  history  of 
tapeworms;  Their  parasitism. 

CHAPTER  XV 

T^niasls 174 

General  consideration  of  the  effect  of  tapeworms  upon  their  hosts;  Tape- 
worms of  the  horse;  Tapeworms  of  cattle,  sheep,  and  goats;  Tapeworms  of 
the  dog;  Dog  tapewomis  in  relation  to  human  infection;  Tapewonns  of 
the  cat;  Tapeworms  of  the  rabbit;  Characteristics  of  the  family  DiphyUo- 
bothriidae;  Occurrence  of  species;  Treatment  of  tseniasis  of  the  dog;  Pre- 
vention; Treatment  of  tseniasis  of  the  cat;  Treatment  of  tseniasis  of  sheep, 
goats,  and  cattle;  Treatment  of  ta?niasis  of  the  horse. 


CHAPTER  XVI 

Tapeworms  of  Chickens 189 

Characteristics  of  species;  Investigations  as  to  their  relative  occurrence; 
Symptoms;  Control;  Treatment. 


CONTENTS  xi 

CHAPTER  XVII 

PAGE 

The  Tapeworm  Larv^ 194 

Pathologic  importance;  Forms  and  their  characteristics,  Cysticercosis 
or  measles;  Beef  measles;  Its  occurrence;  Degeneration  and  vitality  of  the 
cysts;  Pork  measles,  Its  occuri'ence;  Degeneration  and  vitality  of  the  cysts; 
Measles  of  the  sheep;  Ccenurosis  or  gid;  Its  occurrence;  Its  development; 
Its  post-mortem  appearance;  Its  sj-mptoms;  Control  and  treatment;  Echin- 
ococcosis or  hj'datid  disease;  Structure  of  the  echinococcus  cyst;  Its  de- 
velopment; Post-mortem  appearance  in  echinococcosis;  Sj-mptoms;  Con- 
trol. 

CHAPTER  XVIII 

Phylum  III.    Ccelhelminthes;  The  Smooth  and  Segmented  Roundworms  .  .  .  216 
Characteristics  of  the  Ccelhelminthes;  Characteristics  of  the  class  Xe- 
mathelminthes;  Characteristics  of  the  order  Xematoda:  Parasitism  of  the 
nematode  worms  in  general;  General  considerations  as  to  treatment. 

CHAPTER  XIX 

Nematoda;  Family  I.  AscARro^E;  The  Large  Roundworms  of  the  Intestine  229 
Characteristics  of  the  Ascaridse;  Investigations  as  to  life  history;  Ascar- 
iasis;  Ascarids  of  the  horse;  Occurrence  of  equine  ascariasis;  Its  etiology, 
control,  and  treatment;  Characteristics  of  the  famih-  Oxjairidse;  Oxyuriasis 
of  equines;  Ascarids  of  the  dog  and  cat;  Ascarids  of  the  hog  and  -sheep;  As- 
carids of  the  ox;  The  family  Heterakida)  and  heterakiasis  of  poultry. 

CHAPTER  XX 

Nematoda;  Family  IV.   Filariid^e;  The  Thread-like  Worms 244 

Characteristics  of  the  Filariida?;  Parasitism;  Filaria  of  the  horse;  Their  oc- 
currence; Effect  of  filariasis  upon  equines;  Filaria  of  sheep  and  cattle;  Filaria 
of  the  dog;  Hematic  filariasis;  Filaria  of  the  hog;  Filaria  of  poultry. 

CHAPTER  XXI 

Nematoda;  Family  V.     Strongylid^e;  Subfamily  I.     Metastrongylin^ 

Worms  of  the  Respiratory  Tract 255 

Characteristics  of  the  Strongylidse ;  Parasitism;  Strongylosis;  Characteris- 
tics of  the  JNIetastrongj-linse;  Parasitism;  Bronchial  and  pulmonary  strongy- 
losis of  the  sheep  and  goat;  Its  symptoms,  course,  and  prognosis;  Bronchial 
and  pulmonary  strongylosis  of  cattle;  Its  symptoms,  course,  and  prog- 
nosis; Bronchial  and  pulmonary  strongylosis  of  the  pig;  Its  occurence  and 
sj-mptoms;  Bronchial  and  pulmonary  strongjdosis  of  the  horse;  Cardio- 
pulmonary strongj'losis  of  the  dog;  Pulmonary  strongylosis  of  the  cat;  Post- 
mortem appearance  in  bronchial  and  pulmonary  strongj'losis;  Develop- 
ment, etiology,  control,  and  treatment  of  bronchial  and  pulmonary  strongj'- 
losis. 


xii  CONTENTS 

CHAPTER  XXII 

PAGE 

Nematoda;  Subfamily  IT.     Trichostroxgylin.e;  Worms  of  the  STOiiACH 

AND  Intestine 268 

Characteristics  of  the  Trichostrongylinse ;  Parasitism;  Gastro-intestinal 
strongylosis  of  the  sheep  and  goat;  Its  occurrence;  Its  symptoms;  Gastro- 
intestinal strongylosis  of  cattle;  Its  occurrence;  Its  symptoms;  Post-mortem 
appearance  in  gaslro-intestinal  strongylosis,  Development,  etiology,  con- 
trol, and  treatment  of  gastro-intestinal  strongj'losis. 


CHAPTER  XXIII 

Nematoda;  Subfamily  III.    Stroxgylin.e;  Worms  of  the  Large  and  Small 

Intestines;  Other  Strongyles 280 

Characteristics  of  the  Strongylinae;  Parasitism;  Nodular  strongylosis  of 
the  sheep  and  goat;  Its  occurrence;  Its  development;  Its  post-mortem  ap- 
pearance; Its  symptoms;  Treatment;  Nodular  strongylosis  of  cattle;  Nodu- 
lar strongylosis  of  the  hog;  Strongylosis  of  the  large  intestine  of  the  sheep  and 
goat;  Strongylosis  of  the  intestines  of  the  horse;  Its  development;  Its  symp- 
toms; Its  post-mortem  appearance;  Intestinal  strongylosis  of  the  dog  and 
cat;  Other  Strongyhnse;  Tracheal  strongylo.sis  of  chickens;  The  kidney 
worm  of  the  hog;  Family  Eustrongylidse  and  eustrongylosis. 


CHAPTER  XXIV 

Nematoda;  Family  VII.    Trichinellid.e 299 

Characteristics  of  the  Trichinellidae ;  The  "whip-worms"  of  the  large 
intestine;  Tnchinclla  spiralis  and  trichinosis;  Life  history  of  Trichinella 
spiralis;  Intestinal  trichinosis;  Muscular  trichinosis;  Degeneration  of  the 
trichina  cyst;  Infection;  Symptoms  of  intestinal  and  muscular  trichinosis  in 
hogs;  Trichinosis  in  rats  and  mice;  Prophylaxis. 

CHAPTER  XXV 

The  Thorn-headed  Worm;  The  Leeches 306 

Characteristics  of  the  order  A(;anthocephala;  The  thorn-headed  worm  of 
the  intestines  of  the  hog;  Its  life  history;  Its  occurrence;  Its  pathogenicity; 
Symptoms  produced;  Treatment;  Characteristics  of  the  class  Annelida; 
Characteristics  of  the  order  Hirudinea;  The  horse  leech;  The  medicinal 
leech;  Sources  of  infestation  by  leeches;  Their  effect  upon  the  animal  at- 
tacked; Treatment. 


CONTENTS  xiii 

PART  III 

■THE  PATHOGENIC  PROTOZOA 

CHAPTER  XXVI 

PAGE 

PHYLrji  IV.    Protozoa 311 

General  consideration  of  the  Protozoa;  Characters  differentiating  Pro- 
tozoa from  Metazoa;  Ameba,  its  main  features  for  study;  Parasitism  of 
the  Protozoa;  Progress  of  research;  Relationship  of  arthropods  to  infection 
with  protozoal  diseases;  Evolution  of  pathogenicity  in  Protozoa;  Methods 
of  reproduction  in  free  and  parasitic  forms;  Life  history  of  the  malaria  or- 
ganisms; The  schizogonic  or  asexual  cycle;  The  sporogonic  or  sexual  cycle; 
Classification  of  pathogenic  species. 

CHAPTER  XXVII 

The  Protozoan  Subgroups;  Diseases  Due  to  Protozoa 324 

Characteristics  of  the  class  Rhizopoda;  Infectious  entero-hepatitis  of  tur- 
keys; Amebic  dysentery  of  man;  Characteristics  of  the  class  Flagellata; 
Characteristics  of  the  order  Spirochetida;  Spirochetosis  of  poultry;  Char- 
acteristics of  the  order  Trypanosomatida;  Parasitism;  Transmission  of 
the  infecting  organisms;  Nagana  or  "fly  disease;"  Surra,  Mai  de  Caderas; 
Dourine;  Trypanosoma  aviericanurn;  Characteristics  of  the  class  Sporozoa; 
Characteristics  of  the  order  Coccidia;  Coccidiosis;  Eimeria  stiedce;  Cocci- 
diosisof  rabbits;  Diplospora  bigemina;  Coccidiosis  ot  dogs;  Coccidium  zurni; 
Red  dysentery  of  cattle;  Eimeria  avium;  Coccidial  enteritis  of  chicks;  Char- 
acteristics of  the  order  Hemosporidia;  Piroplasma  higeminum;  Texas-fever 
of  cattle;  Its  occurrence;  Exposure  and  development;  Its  symptoms;  The 
acute  type;  The  chronic  type;  Prevention  and  treatment;  Characteristics  of 
the  order  Sarccsporidia;  Sarcosporidiosis;  Mode  of  infection. 

Glossary 353 

Index 359 


LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

1.  Diagram  of  an  insect 16 

2.  Diagram  of  internal  parts  of  an  insect 16 

3.  Diagram  of  insect's  heart 17 

4.  Mouth  parts  of  a  biting  insect 17 

5.  Diagram  showing  tracheal  system  of  an  insect 18 

6.  Abdomen  of  locust,  showing  spiracles IS 

7.  Head  of  bee,  showing  compound  eyes,  ocelli,  and  antennse 19 

8.  Metamorphosis  of  the  house  fly 19 

9.  Diagram  of  segments  of  arthropod,  showing  leg  muscles,  etc 19 

10.  Eggs  and  larvse,  of  Culex  mosquito 2-4 

11.  Pupa,  of  Culex  and  Anopheles  mosquitoes 26 

12.  Culex  pungens,  male  and  female 27 

13.  Anopheles  quadrimaculatus,  male  and  female 28 

14.  Position  of  Anopheles  and  Culex  at  rest 28 

15.  Breathing  position  of  larva,  of  Anopheles  and  Culex 29 

16.  Eggs  of  Anopheles 30 

17.  The  Southern  buffalo  gnat 32 

18.  Larva  of  Southern  buffalo  gnat 33 

19.  Pupa  of  Southern  buffalo  gnat 33 

20.  The  black  horsefly 36 

21.  The  green-head  fly 36 

22.  The  stable  or  stinging  fly 39 

23.  The  horn  fly 42 

24.  Tsetse  fly 44 

25.  The  "sheep  tick." 47 

26.  The  screw  worm  fly 51 

27.  Metamorphosis  of  the  flesh  fly 52 

28.  Horse  botfly,  showing  eggs,  larva,  and  adult 54 

29.  Ox  botfly,  Hypoderma  Uneata 58 

30.  Ox  botfly,  Hypoderma  bovis 59 

31.  Eggs  of  Hypodemia  lineata 59 

32.  Larval  stages  of  Hj^poderma  lineata _,.  61 

33.  The  sheep  botfly,  showing  larva,  pupa,  and  adult 63 

34.  The  dog  flea,  anterior  portion  of  body 66 

35.  The  human  flea,  anterior  portion  of  Ijodj- 66 

36.  The  dog  flea,  showing  development  and  mouth-parts 67 

37.  Larva  of  flea 68 

38.  Sucking  louse  of  horse,  Hsematopinus  asini 73 


<vi  LIST   OF  ILLUSTRATIONS 

IG.  PAGE 

39.  Biting  louse  of  horse,  Trichodectes  parumpilosus 73 

40.  Sucking  louse  of  cattle,  Ha?matopiuus  eurysternus 74 

41.  Sucking  louse  of  calves,  Linognathus  (Haematopinus)  vituli 75 

42.  Biting  louse  of  cattle,  Trichodectes  scalaris 75 

43.  Sucking  louse  of  sheep,  Linognathus  (Hsematopinus)  pedalis 76 

44.  Biting  louse  of  sheep,  Trichodectes  sphiprocephalus 77 

45.  Sucking  louse  of  hog,  Hsematopinus  suis 78 

46.  Sucking  louse  of  dog,  Linognathus  (Hsematopinus)  piliferus 78 

47.  Biting  louse  of  dog,  Trichodectes  latus 79 

48.  Louse  of  the  cat,  Trichodectes  subrostratus 79 

49.  Louse  of  chicken,  Goniocotes  gigas  (G.  abdominalis) 83 

50.  Louse  of  chicken,  Lipeurus  caponis  (L.  variabihs) '.  .  83 

5L  Louse  of  chicken,  Menopum  trigonocephalum  (Menopon  pallidum) .  83 

52.  Louse  of  turkey,  Goniodes  stylifer 85 

53.  Louse  of  turkey,  Lipeurus  meleagridis  (L.  poly  trapezius) 85 

54.  Louse  of  turkey,  Menopum  (Menopon)  biseriatum 85 

55.  Louse  of  duck,  Lipeuris  anatis  (L.  squalidus) 85 

56.  Louse  of  ducks  and  geese,  Trinotum  (Trinoton)  luridum 87 

57.  Louse  of  swan,  Philopterus  (Docophorus)  cygni 87 

58.  Louse  of  swan,  Ornithonomus  (Ornithobius)  cygni 87 

59.  Louse  of  pigeon,  Goniocotes  conipar 87 

60.  Louse  of  pigeon,  Goniodes  damicornis 87 

6L  Bedbug,  adult  female,  mouth-parts  etc 91 

62.  Diagram  of  the  anatomy  of  a  spider 95 

63.  Gamasid  poultry  mite,  young  and  adult 98 

64.  Mange  mite  of  horse 104 

65.  Mange  mite  burrow  in  human  skin 105 

66.  Colts  affected  with  sarcoptic  mange 106 

67.  Leg  scab  mite  of  horse 109 

68.  Scab  mite  of  sheep,  female Ill 

69.  Scab  mite  of  sheep,  male HI 

70.  Follicular  mange  mite 116 

71.  Mange  mite  of  cat  and  rabbit 118 

72.  Auricular  scab  mite  of  rabbit 118 

73.  Portable  dipping  vat  for  sheep 127 

74.  Mite  of  scaly  leg  of  poultry,  male  and  female 133 

75.  Foot  of  fowl  affected  with  scaly  leg 134 

76.  Capitulum  of  tick 137 

77.  Capitulum,  scutum,  and  fore  leg  of  Texas  fever  tick 137 

78.  Stigmal  plates  of  ticks  Margaropus,  Ixodes,  and  Dermacentor.  .  .  .  138 
78a.  Photomicrograph  of  stigmal  plate  of  Texas  fever  tick 138 

79.  Fowl  tick,  adult  and  larva 139 

80.  Spinose  ear  tick,  nymphal  form 141 


LIST   OF   ILLUSTRATIONS  xvii 

FIG.  PAGE 

81.  The  castor-bean  tick 143 

S2.  The  American  dog  or  wood  tick 144 

83.  Linguatula  rhinaria 153 

84.  Planarian  wonn 156 

85.  Liver  fluke,  Fasciola  hepatica 157 

86.  Reproductive  organs  of  liver  fluke 158 

87.  Fasciola  hepatica,  F.  americanus,  Dicrocceliuni  lanceatum 161 

88.  Life  history  of  Hver  fluke 162 

89.  Blood  fluke,  male  and  female 168 

90.  Segment  of  Taenia  saginata,  showing  sexual  organs 171 

91.  Tapeworms  of  the  horses 175 

92.  Tapewonn  of  cattle  and  sheep,  Moniezia  expansa 176 

93.  Fringed  tapeworm  of  sheep,  anterior  segments 177 

94.  Tapewonn  of  dog,  Dipjdidium  caninum ISO 

95.  Rostellum  of  Dipylidium  caninum 180 

96.  Egg  packet  and  Cysticercoid  of  Dipylidium  caninum 180 

97.  Tapeworm  of  dog.  Taenia  hydatigena 180 

98.  Tapeworm  of  dog,  Taenia  pisiformis 180 

99.  Tapewonn  of  dog,  Echinococcus  granulosus 180 

100.  Rostellum  of  tapewonn  of  cat.  Taenia  taeniaeformis 184 

101 .  Diphyllobothriimi  latum 186 

102.  Tapewonn  of  chicken,  Clioanotsenia  infundibulifonnis 189 

103.  Scolex  of  Choanotaenia  infundibulifonnis 190 

104.  Scolex  of  Davainea  tetragona  of  chicken 190 

105.  Scolex  of  Davainea  echinobothrida  of  chicken 190 

106.  Tapeworm  of  man,  Taenia  saginata 196 

107.  Diagram  of  Cysticercus 198 

108.  Fragment  of  beef  muscle,  showing  cysts  of  Cysticerus  bovis 198 

109.  Scoleces  of  Taenia  solium,  T.  saginata,  and  DiphA'llobothrivun  Latum .  .  .  199 

110.  Eggs  of  Taenia  saginata  and  T.  solium 200 

111.  Alature  segments  of  Taenia  saginata  and  T.  solium 200 

112.  Stages  in  tapeworm  development 201 

113.  Portions  of  adult  gid  tapeworm,  Multiceps  multicejis 205 

114.  Diagrammatic  section  of  Multiceps  (Coenurus)  cyst 206 

115.  Brain  of  lamb,  showing  furrows  produced  by  young  gid  bladderwonn. .  206 

116.  Gid  bladderwonn,  showing  immature  tapewonn  heads 206 

117.  Diagram  of  Echinococcus  hydatid 211 

118.  Echinococcus  granulosus,  showing  hydatid  with  brood  capsules 214 

119.  Transection  of  Ascaris  equi 217 

120.  Posterior  extremit^^  of  male  nematode  worm 218 

121.  Cephalic  extremity'  of  an  ascarid  worm 229 

122.  Ox^vuris  equi 236 

123.  Belascaris  marginata,  showing  head  and  male  and  female 238 


xviii  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

124.  Egg  of  Ascaris  lumbricoides 240 

125.  Ascaris  lumbricoides,  male  and  female 240 

126.  Heterakis  perspicillum,  male  and  female,  and  H.  vesicularis  of  poultrj^  242 

127.  Setaria  labiato-papillosa,  male  and  female 245 

128.  Gong5donema  scutata,  anterior  and  posterior  views 247 

129.  Dirofilaria  imonitis,  male  and  female 249 

130.  Lung  wonn  of  sheep  and  goat,  Dictj'-ocaulus  filaria,  male,  female,  and 

eggs 257 

131.  Lung  wonn  of  sheep,  goat,  and  rabbit,  Synthetocaulus  rufescens,  male 

and  female 257 

132.  Lung  worm  of  cattle,  Dictyocaulus  viviparous 259 

133.  Lung  worm  of  pig,  Metastrongylus  apri,  male  and  female 260 

134.  Stomach  worm  of  sheep,  goat,  and  cattle,  Hsemonchus  contortus, 

female 269 

135.  Hsemonchus  contortus,  anterior  portion  of  body 269 

136.  Hsemonchus  contortus,  enlarged  posterior  extremity  of  male 269 

137.  Cooperia  curticei,  male  and  female 270 

138.  Cooperia  curticei,  enlarged  anterior  portion 270 

139.  Ostertagia  marshalli,  male  and  female 270 

14Q.  Trichostrongylus  instabiUs,  male  and  female 271 

141.  Ostertagia  ostertagi,  male  and  female 273 

142.  Ostertagia  ostertagi,  posterior  extremity  of  male  enlarged 273 

143.  Nematodirus  fihcollis,  male  and  female  and  enlarged  anterior  portion .  .   274 

144.  Cooperia  oncophora,  male  and  female 274 

145.  (Esophagostomum  columbianmn,  male  and  female 282 

146.  QEsophagostomum  columbianum,  enlarged  anterior  portion 282 

147.  (Esophagostomum  colmnbianum,  enlarged  bursa  of  male 283 

148.  (Esophagostomum  venulosum,  male  and  female 283 

149.  (Esophagostomum  venulosum,  enlarged  anterior  portion 283 

150.  (Esophagostomum  venulosum,  enlarged  bursa  of  male 283 

151.  (Esophagostomum  radiatum,  male  and  female 286 

152.  (Esophagostomum  radiatum,  enlarged  anterior  portion • 286 

153.  (Esophagostomum  radiatum,  enlarged  bursa  of  male 286 

154.  Chabertia  ovina,  male  and  female 287 

155.  Strongjdus  equinus,  male  and  female 288 

156.  Hook-worm  of  dog  and  cat,  Ankylostoma  canina,  male  and  female .  .   292 

157.  Bunostomum  phlebotomum,  male  and  female 293 

158.  Tracheal  wonn  of  poultry,  Syngamus  trachealis,  male  and  female.  .   294 

159.  Dioctophjine  renale,  male 297 

160.  Trichuris  ovis,  male  and  female 300 

161.  Trichuris  ovis,  egg 300 

162.  Trichinella  spiralis,  male  and  female 301 

163.  Trichinella  spirahs,  encysted  larva  in  muscle 302 


LIST   OF  ILLUSTRATIONS  xix 

FIG.  PAGE 

164.  Trichiuella  spiralis,  microphotograph  of  cyst 304 

165.  The  thorn-headed  wonii,  Gigautorhjnichus  hirudinaceus 307 

166.  Cephalic  extremity  of  thorn-headed  wonn 307 

167.  The  horse  leech 308 

168.  Anieba  proteus 312 

169.  Spirocheta  palhda 327 

170.  Hen  sufTering  from  acute  spirochetosis .• 328 

171.  Piroplasma  bigeminum 348 

172.  Fonns  of  Sarcosporidia,  shown  in  infected  muscle 351 

Plates.  Page 

I.  Texas  fever  tick,  male  and  female,  with  details 146 

II.  Texas  fever  tick,  stages  of  engorgement  and  details 147 

III.  Evolution  of  the  parasite  of  kala-azar 317 

IV.  Life  cycle  of  the  malaria  parasite 321 

V.  Various  species  of  Trypanosoma 331 

YI.  Percheron  stallion  before  and  after  development  of  dourine 338 

VII.  Percheron  mares,  sho\\'ing  chronic  dourine  and  last  stage 340 

VIII.  Coccidian  life  cycle 344 

TABLES 

Classification  of  parasites  of  the  class  Insecta 20 

Life  history  of  horse  botfly,  Gastrophilus  equi 55 

Life  history  of  sheep  botfly,  (Estrus  ovis 63 

Classification  of  parasites  of  the  class  Arachnida 96 

Sunmaary  on  nonparasitic  periods  in  de^•elopment  of  Texas  fever  tick 149 

Sunmiary  on  parasitic  periods  in  development  of  Texas  fever  tick 150 

Life  histories  of  dog  tick  and  Texas  fever  tick  compared 151 

Classification  of  parasites  of  the  phylum  Platyhehninthes 157 

Life  history  of  liver  fluke,  Fasciola  hepatica 163 

Life  history  of  beef  tapewonn.  Taenia  saginata 172 

The  principal  tapewomis,  with  their  larvfe  and  hosts 173 

Synopsis  of  tapewonn  larvse 194 

Life  history  of  the  gid  tapewonn,  Multiceps  multiceps 207 

Life  history  of  Echinococcus  granulosus 213 

Classification  of  parasites  of  the  phylum  Coelhelminthes 222 

Life  history  of  Trichinella  spiralis 303 

Classification  of  parasites  of  the  phylum  Protozoa 322 


PARASITES  AND  PARASITOSIS  OF  THE 
DOMESTIC  ANIMALS 


PARASITES  AND  PARASITOSIS  OF  THE 
DOMESTIC  ANIMALS 

PART   I 

PRELOIIXARY   CHAPTERS 

THE  EXTERNAL  PARASITES 

CHAPTER  I 
INTRODUCTION 

The  earth's  vast  hiboratory  of  hvmg  matter  inchides  a  flora  and  fauna 
in  which  all  of  the  hiohly  diversified  forms  encomiter  conditions  operating 
to  restrict  their  miiltiphcation  and  to  govern  the  predominance  of  cer- 
tain forms  over  others.  These  contUtions  are  constituted,  first,  by 
topographic  and  climatic  variations  rendering  certain  localities  more  or 
less  inhospital)le  to  some  organisms,  while  others  may  be  uninfluenced  or 
perhaps  benefited.  Second,  there  is  the  behavior  of  living  things  toward 
one  another;  this  may  l)e  relatively  harmonious  or  there  may  be  an 
intense  rivalry  in  which  organisms  encroach  or  prey  one  upon  the  other, 
the  least  fit  for  the  strife  being  driven  to  less  favorable  habitats,  progres- 
sively dwarfed,  or  ultimately  becoming  extinct.  Though  most  of  these 
inhibitive  influences  are  not  apparent  to  cursory  observation,  the}'  are, 
nevertheless,  numerous  and  varied  as  well  as  constant  in  their  operation, 
constituting  a  prime  factor  in  the  evolution  and  specialization  of  organic 
forms. 

There  is,  then,  a  perpetual  struggle  for  existence,  which  may  lead  to 
the  seeking  of  shelter  from  the  conflict  in  a  changed  and  often  degenerate 
mode  of  life  to  which  the  organism  becomes  adaptively  modified.  Thus, 
through  such  uifluences,  a  terrestrial  animal  may  be  driven  to  an  ar- 
boreal, or  even  an  aquatic  or  semiaquatic,  existence.  A  defenseless  Httle 
member  of  the  Insectivora  burrows  and  becomes  subterranean,  while 
another  finds  protection  in  the  nocturnal  habit;  others  seek  the  shelter 
of  caves  or  rock  crevices,  and  we  often  find  creatures,  usually  somewhat 
degenerate,  in  places  which  seem  to  us  quite  unfavorable  to  their  sup- 
port.   While  in  such  cases  the  animal  continues  to  lead  a  free  and  in- 


2  PARASITES  OF  THE  DOMESTIC  ANIMALS 

dependent,  often  solitary  existence,  on  the  other  hand,  a  communion  of 
life's  interests  may  be  estabhshed  between  two  organisms  which,  it  is 
surmised,  is  founded  upon  some  nmtual  advantage  in  the  strife.  To 
such  association  the  general  term  s>Tiibiosis  has  been  applied  and  each 
of  the  organisms  concerned  is  referred  to  as  a  SAaubiont.  Though  there 
is  by  no  means  a  uniformity  in  the  appHcation  of  terms  referring  to  the 
symbiotic  relationship,  a  usage  is  adopted  here  that  seems  best  defined, 
and  by  which  s>mibiosis  is  subdivided  into  the  three  categories,  (1)  mu- 
tualism, (2)  commensalism,  and  (3)  parasitism.  In  the  first  there  is  a 
reciprocal  advantage  derived  from  the  union;  in  the  second  but  one 
s\Tnbiont  is  benefited  though  the  other  suffers  no  harm,  while  in  the 
third  division  one  receives  an  advantage  to  the  detriment  of  the  animal 
or  plant  which  it  invades.  There  is,  however,  no  sharp  line  of  demarca- 
tion between  these  three  states  of  living  together,  and  it  may  be  difficult 
to  determine  in  some  cases  whether  one  or  both  symbionts  receives 
benefit  from  the  union,  or  whether  one  is  or  is  not  injured  by  it. 

One  of  the  more  obvious  examples  of  mutualism  is  the  case  of  the- 
hermit  crab  and  the  sea  anemone.  This  crab  selects  a  shell,  as  that  of 
the  whelk,  for  its  habitation,  from  the  opening  of  which  it  projects  only 
its  head  and  claws.  On  the  surface  of  the  shell  may  often  be  found  a  sea 
anemone  fastened  near  the  opening  with  its  mouth  and  tentacles  in  the 
vicinity  of  the  crab's  head.  The  anemone  in  this  position  not  only  in  a 
measure  serves  to  conceal  the  hermit  crab  from  its  enemies,  but  the 
creature  that  would  prey  upon  the  crab  must  first  reckon  with  the 
dangerous  stinging  threads  with  which  the  tentacles  of  the  anemone  are 
armed.  The  anemone,  in  its  turn,  is  benefited  by  being  carried  about 
by  the  crab  and  aided  in  this  way  in  obtaining  its  food. 

Such  associations  are  not  always  of  mutual  advantage,  and  maj'  be 
more  in  the  nature  of  an  invasion  of  one  animal  upon  or  within  the 
body  of  another,  the  invading  animal  alone  deriving  benefit,  while  the 
animal  upon  which  the  association  is  forced,  though  not  benefiting, 
ma}^  in  no  way  suffer  from  it.  A  familiar  form  of  this  living  together 
(commensalism)  is  the  little  crab  so  commonly  found  in  the  shell  of  the 
oyster.  The  oyster  is  not  harmed  by  its  presence,  but  the  crab  is  bene- 
fited by  the  protection  which  the  shell  affords.  Another  more  curious 
example  of  such  association  is  afforded  among  the  vertebrates  by  the 
species  of  Remora,  or  suck  fishes,  which  have  the  first  dorsal  fin  modified 
into  a  sucking  disk  on  top  of  the  head.  By  means  of  this  disk  it  attaches 
itself  to  a  shark  or  other  large  fish,  and  is  thus  carried  about,  detaching 
itself  only  to  secure  food.  Its  benefit  from  such  association  is  in  being- 
carried  to  new  feeding  grounds  without  effort  of  its  own,  and  in  the 
shelter  from  its  enemies  which  the  body  of  the  larger  fish  may  afford. 
The  host,  on  the  other  hand,  cannot  be  benefited,  nor  does  it  seem  to 
suffer  by  the  presence  of  its  uninvited  guest. 


INTRODUCTION  3 

AVhether  this  relationship  between  different  species  is  of  reciprocal 
advantage  or  of  benefit  to  but  one,  neither  of  the  s\anbionts  lives  upon 
or  at  the  expense  of  its  co-sjnnbiont,  and  neither  has  entirely  renounced 
its  independence.  In  true  parasitism  the  invading  animal  lives  upon  the 
tissues  of  its  host,  deprives  it  of  a  portion  of  its  nourishment;  or  is  in 
other  wa3'S  injurious  to  it.  There  are  many  examples  of  this  form  of 
symbiosis,  and  students  of  animal  life  are  familiar  with  the  conditions 
that  seem  always  to  attend  it,  such  as  the  degenerative  and  adaptive 
modifications  occurrmg  in  the  parasite. 

It  is  the  common  habit  of  many  animals,  however,  to  prey  upon  the 
bodies  of  other  animals,  and  we  should  distinguish,  so  far  as  we  may, 
between  those  which  are  predatory  and  those  which  are  parasitic.  The 
former  are  free  and  exercise  their  powers  of  sense  and  cunning  in  snarmg 
or  chasing  their  pre}',  while  the  latter,  in  fully  acquired  parasitism,  live 
on  or  in  the  bodies  of  their  victims,  often  burrowing  into  and  consummg 
the  bod}'  tissues,  leading  a  lazy,  beggarly  existence  in  which  all  of  the 
faculties  of  special  sense  and  prowess,  so  highly  developed  m  predatoiy 
animals,  become  degenerate  and  atrophied. 

Parasitism  is  found  throughout  the  range  of  animal  life  from  the 
unicellular  to  the  vertebrate,  and,  though  a  sharp  distinction  between 
predaceous  and  parasitic  animals  may  not  be  made,  in  view  of  the  de- 
grading influence  of  the  parasitic  habit,  the  difference  between  the 
simplicit}^  of  degeneration  and  the  simplicity  of  primitiveness  should  be 
clearly  defined.  In  the  development  of  a  primitively  simple  animal  the 
young  stages  are  more  simple  than  in  the  adult  and  it  has  only  simple 
ancestors.  In  the  degenerate  animal,  on  the  other  hand,  the  ancestors  are 
often  more  complex  and  the  young  stages  are  of  a  higher  grade  than  the 
stage  of  the  adult.  The  adoption  of  any  mode  of  life  which  withdraws 
from  the  activities  necessar}^  to  survival  in  a  free  existence  seems  to 
bring  about  this  condition  of  degradation.  Of  this  we  have  a  remarkable 
example  outside  of  the  realm  of  parasitism  in  the  Tunicata.  These 
aberrant  animals,  in  the  stage  of  the  free-swimming  larva,  have  a  chordal 
axis  which  in  nearly  all  of  the  different  species  becomes  entirely  lost 
before  they  reach  maturity.  After  passing  the  "tadpole"  stage  there 
follows  an  extreme  specialization  to  the  fixed  habit  which  most  tunicates 
retain  throughout  their  adult  life,  becommg  what  are  commonly  known 
as  sea  squirts,  mere  attached,  plant-like  sacs,  emitting  a  jet  of  water 
when  disturbed,  and  from  Avhich  all  chordate  features  have  been  entirely 
lost. 

The  degenerative  changes  which  a  parasite  undergoes  concern  mostly 
the  nervous  system,  the  organs  of  locomotion,  and  those  of  nutrition,  the 
nervous  system  becoming  reduced  to  the  most  indispensable  portion, 
while  of  the  sense-organs  nothing  may  be  left  except  those  of  touch.  The 
locomotor  apparatus  may  become  modified  into  claws  or  hooks  for 


4  PARASITES  OF  THE  DOMESTIC  ANIMALS 

clasping  the  hairs  of  the  host,  or  it  may  ahiiost  if  not  completely  dis- 
appear and  be  replaced  b}^  such  organs  of  fixation  as  sucking-disks.  As 
the  contents  of  the  alimentary  canal  or  tissue  fluids  of  the  host  upon 
which  the  verminous  parasite  is  nourished  need  scarcely  any  digestion, 
the  digestive  organs  become  simplified  or  may  be  quite  lost,  the  absorb- 
tion  of  nutriment  in  the  latter  case  taking  place  entirely  through  the 
body  integument,  as  in  some  of  the  worms  which  infest  the  intestines  of 
man  and  other  animals.  The  degree  of  decadence  will  depend  upon  the 
degree  of  dependence  upon  the  host.  In  this  latter  respect  the  parasitism 
may  be  optional,  as  in  the  case  of  the  mosquito,  which  may  live  upon  the 
juices  of  plants  but  prefers  a  meal  of  warm  blood,  or  it  may  be  obligate, 
depending  upon  another  for  its  means  of  subsistence,  though  such 
obligate  parasites  as  the  biting  flies,  fleas,  and  bedbugs  may  also  live 
free  and  only  occasionly  visit  their  hosts,  a  form  of  parasitism  which 
may  be  accompanied  by  little  modification  of  the  adaptability  to  a  free 
life'. 

In  the  event  of  the  parasite  becoming  progressively  degraded  into  one 
which  not  only  seeks  its  host  for  food,  but  has  become  dependent  upon 
it  for  both  its  nutrition  and  place  of  abode,  all  of  the  above  mentioned 
phenomena  of  adaptation  become  more  conspicuous.  There  is  furnished 
a  very  good  example  of  such  a  transformation  in  the  sheep  tick  (Melo- 
phagiis  ovinus),  not  a  true  tick,  however,  but  a  fly  which,  originally  an 
occasional  visitor,  has,  like  the  louse,  taken  permanent  abode  upon  its 
host.  No  longer  taking  the  aerial  flight  of  its  discarded  free  life,  this 
fly  has  become  wingless,  and,  furthermore,  is  enabled  to  pass  its  entire 
life  cycle  upon  the  body  of  the  host  animal  by  a  remarkable  method  of 
reproduction  involving  the  retention  of  the  eggs  in  the  oviducts  until 
development  has  passed  through  the  larval  stage.  It  is  not  until  ready  to 
pass  into  the  stage  of  the  pupa  that  the  larva?  are  extruded,  the  pupal 
case  then  being  attached  to  the  individual  wool  fibers.  From  this  case 
the  young  insect,  on  becoming  sufficiently  developed,  makes  its  escape 
and  proceeds  to  feed  and  grow,  thus  rounding  out  a  complete  parasitic 
cycle. 

While  the  easy  life  of  the  parasite  tends  to  degeneration,  the  perpetua- 
tion of  the  species  becomes  more  precarious,  and  the  organs  of  reproduc- 
tion undergo  a  marked  development.  If  a  host  animal  dies  most  of  its 
parasites,  especially  those  existing  in  the  interior  of  its  body,  die  with 
it,  and,  were  it  not  that  the  eggs  find  lodgment  in  a  new  host,  the  parasitic 
species  would  in  a  short  time  become  extinct.  The  transmission  of  but 
few  of  these  eggs  is  successfully  accomplished,  and  in  compensation  they 
must  be  produced  in  enormous  numbers,  well  protected  from  the  many 
elements  of  destruction  which  they  encounter.  The  mode  of  reproduc- 
tion is  one  of  the  principal  factors  determining  the  conditions  of  par- 
asitism,  and,   while  the  above  modifications  pertain  more  to  those 


INTRODUCTION  5 

dwelling  continuously  upon  or  within  the  bodies  of  their  hosts,  we  have 
in  the  ffistridse,  among  the  dipterous  insects,  a  cycle  involving  internal 
parasitism  duruig  the  larval  stage,  a  familiar  example  being  the  common 
horse  botfly  (Gastrophilus  intestinalis) ,  the  development  of  which  is 
given  on  page  54.  It  is  plain  that  a  very  small  percentage  of  the  eggs 
deposited  by  this  fly  can  reach  the  horse's  mouth,  and  that,  having  got 
thus  far,  many  of  the  larvae  must  be  destroyed  or  pass  entirely  through 
the  intestinal  tract  without  having  succeeded  in  becoming  fixed  to  the 
mucous  membrane.  For  this  there  seems  to  be  compensation  in  the 
large  number  of  eggs  deposited  by  the  persistent  female. 

While  in  some  cases  the  complete  life  cycle  of  a  parasite  requires  but 
one  host,  often,  for  reasons  stated  in  the  foregoing,  two  successive  and 
generally  specifically  different  hosts  are  required.  A  rather  compli- 
cated example  of  the  latter  case  is  the  life  history  of  the  common  liver 
fluke  (Fasciola  hepatica),  one  of  the  flat  worms  infesting  in  its  adult 
state  the  livers  of  Herbivora.  It  will  be  noted  in  referring  to  the  cycle  of 
this  parasite,  given  in  detail  elsewhere  (page  160),  that  it  is  a  very 
hazardous  one,  and  that  its  completion  must  depend  upon  the  co- 
operation of  numerous  favorable  conditions.  The  eggs,  of  which  each 
individual  fluke  is  capable  of  producing  in  the  neighborhood  of  one 
hundred  thousand,  must  reach  the  exterior  amid  surroundings  favorable 
to  their  hatching.  If  hatched,  the  larva  must  escape  its  many  aquatic 
enemies  and  within  a  few  hours  find  a  suitable  snail  host.  Providing  the 
snail  is  not  eaten  by  a  duck,  or  does  not  otherwise  perish  during  this 
phase  of  the  cycle,  it  issues  from  its  host  as  the  free-swimming  cercaria, 
when  it  is  again  liable  to  fall  prey  to  various  small  aquatic  animals. 
Escaping  this  and  })ecoming  encysted,  the  chance  of  any  herbivorous 
animal  coming  along  and  swallowing  it  is  very  small.  The  relation  of 
the  enormous  number  of  eggs,  and  the  number  of  individuals  which  one 
egg  may  produce,  to  the  survival  of  the  species  amid  conditions  fraught 
with  such  dangers  seems  quite  evident. 

In  general  it  may  be  said  as  to  the  propagation  of  parasites  that  their 
prodigious  fecundit}^  and  the  great  vital  resistance  with  which  most  of 
them  are  endowed  enables  species  to  survive  and  perpetuate  their  kind 
amid  varied  destroying  influences  which  otherwise  would  bring  about 
their  extermination.  The  tapeworms  inhabiting  the  intestines  of  man 
and  other  animals,  afford  another  example  of  extreme  parasitism  accom- 
panied by  this  remarkable  development  of  the  reproductive  function. 
Here  is  a  creature  so  altered  to  its  degenerate  existence  that  it  has  be- 
come devoid  of  mouth  and  intestine,  the  body  consisting  of  a  scolex, 
usually  referred  to  as  the  head,  from  which  are  give  off  segments  which 
remain  united  until  there  is  formed,  as  in  Tcenia  saginata  of  man,  a 
band-shaped  colony  of  from  twelve  hundred  to  thirteen  hundred  or 
more,  passing  back  from  the  worm's  attachment  to  a  length  which  may 


6  PARASITES  OF  THE  DOMESTIC  ANIMALS 

exceed  twenty  feet.  After  about  the  six  hundredth,  each  segment  is  a 
mature  and  sexually  complete  individual,  which  later,  as  it  is  pushed  on 
by  new  segments  formed  at  the  head,  becomes  filled  with  fecundated 
eggs.  By  the  successive  detachment  of  these  "ripe"  segments  and  their 
passage  from  the  body  of  the  host,  it  has  been  estimated  that  Taenia 
saginata  might  throw  off  in  a  year  as  many  as  one  hundred  and  fifty 
million  eggs,  of  which  but  an  infinitesimal  number,  as  is  quite  evident, 
will  reach  the  bodj'  of  their  proper  bovine  host  for  larval  development. 
Again,  having  been  so  fortunate,  it  is  improbable  that  the  larvae  will, 
while  living,  reach  the  intestines  of  the  human  host  necessary  for  their 
further  development  into  adult  worms. 

Here,  then,  is  an  animal  well  showing  the  degree  of  degeneration 
which  may  be  reached  in  extreme  parasitism;  there  are  no  organs  of 
locomotion,  no  organs  of  special  sense,  no  organs  of  digestion,  no  organs 
of  respiration,  and  none  of  true  circulation.  The  body  consists  of  a  long 
band  of  connected  segments,  each,  when  mature,  bisexually  complete 
and  in  itself  a  sort  of  independent  reproductive  individual,  the  entire 
energy  of  the  organism  concentrated  upon  the  function  of  reproduction 
that  the  perpetuation  of  the  species  may  be  insured  amid  the  perils  with 
which  this  process  is  beset. 

In  many  forms  permanently  parasitic  there  is  an  early  period  of 
development  in  which  organs  of  locomotion  are  distinctly  present,  but, 
as  the  animal  matures,  these  fail  to  develop  or  become  lost.  If  it  is 
assumed  that  this  gradual  loss  of  organs,  change  of  structure,  and  protec- 
tive transmission  of  the  embryo  to  an  intermediate  host  is  due  to  the 
parasitic  life,  it  seems  reasonable  to  conclude  that  all  of  the  parasitic 
groups  have  been  derived  from  free-living  forms,  and  that,  as  parasitism 
became  a  more  fixed  habit,  such  structural  changes  were  in  the  course  of 
time  brought  about  as  would  make  this  mode  of  life  obhgatory.  A  re- 
view of  the  observed  facts,  then,  in  their  biologic  relationship,  leads  to 
the  conclusion  that  symbiosis,  of  which  parasitism  is  a  form,  has  its 
causative  basis  in  the  struggle  for  existence,  the  symbiotic  association  in 
more  or  less  measure  mitigating  the  hazards  to  one  or  both  symbionts. 
It  further  follows  that,  though  some  forms  have  undergone  an  extreme 
modification,  through  related  contemporary  free-living  types,  their  true 
systematic  position  may  be  established. 


CHAPTER  II 

FORMS  OF  PARASITIS:^I  AND  INFLUENCE  UPON  THE  HOST 

Forms  of  Parasitism 

The  student  of  parasitology  will  be  greatly  aided  by  an  orderly  and 
progressive  pursuit  of  the  subject,  an  elementary'  requisite  to  which  is  a 
broad  conception  of  what  is  implied  b}'  the  various  terms  used  in  the 
chapters  which  are  to  follow.  Those  below  are  not  given  with  the  recom- 
mendation that  the}'  be  memorized  as  to  the  exact  wording  set  forth  in 
their  definitions;  more  essential  is  such  an  understanding  that  examples 
can  readily  be  picked  out,  a  typical  illustration  always  being  in  mind  for 
application  to  the  tenn  at  hand.  With  such  a  conception  the  student 
should  be  able  to  fonnulate  his  own  definitions,  and  this  will  be  of  more 
advantage  to  him  than  accepting  those  set  forth  according  to  the  con- 
ceptions of  another. 

Though  some  of  the  following  tenns  have  been  treated  of  in  foregoing 
introductory  remarks,  the}^  are  here  included  for  more  concise  definition 
and  to  make  the  list  inclusive. 

Symbiosis  is  the  more  or  less  pennanent  living  together  of  two  plants, 
two  animals,  or  an  animal  and  a  plant,  the  union  being  in  a  measure 
beneficial  to  both,  or  to  one  with  or  without  hami  to  the  other. 

Symbiont, — one  of  two  organisms  partaking  of  symbiotic  relationship. 

Mutualism  is  a  fonn  of  sjmibiosis  in  which  both  sjTubionts  are  in 
more  or  less  measure  benefited  by  the  union. 

Commensalism  is  that  form  of  s^inbiosis  in  which  but  one  sjinbiont 
is  benefited,  while  its  co-s\anbiont  is  neither  benefited  nor  harmed  by 
the  union. 

Helotism  is  a  form  of  s}^nbiosis  in  which  one  organism  appears  to 
enslave  the  other,  enforcing  it  to  labor  in  its  behalf.  The  term  is  applied 
to  such  association  in  certain  insects. 

Parasitism  is  that  form  of  sjanbiosis  in  which  one  symbiont,  for  pur- 
poses of  procuring  food,  or  food  and  shelter,  visits  briefly,  or  takes  up 
its  abode  temporarily  or  pennanently,  upon  or  within  the  bodj'  of  its 
co-s>inbiont  which  is  harmed  by  the  union.  The  sAinbiont  receiving 
the  advantage  is  known  as  the  parasite,  to  which  the  one  injured  is  the 
host. 

Phytoparasites  are  parasites  which  belong  with  the  vegetable 
kmgdom. 


8  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Zooparasites  are  parasites  which  belong  with  the  animal  kingdom. 

Optional  Occasional  Parasites  are  those  which  only  fleetingly  visit 
their  hosts  to  obtain  nourishment,  but  are  not  dependent  upon  them  for 
either  nourishment  or  shelter.    Example,  mosquitoes. 

Obligate  Occasional  Parasites  are  those  which  do  not  permanently 
live  upon  their  hosts,  but  are  dependent  upon  them  for  nourishment  and 
to  some  extent  for  shelter.    Examples,  fleas,  bedbugs. 

Determinate  Transitory  Parasites  are  those  in  which  the  parasitism 
is  hmited  to  a  definite  phase  or  phases  in  their  Hfe  history,  during  which 
time  the  parasitism  is  ol:)ligate  and  continuous.  Examples,  botflies, 
ticks. 

Permanent  Parasites  are  those  in  which  the  parasitism  extends  from 
the  hatching  of  the  egg  to  the  stage  of  reJDroduction  in  the  adult.  Exam- 
ples, lice,  many  entozoa. 

Fixed  Parasites  are  those  which  cannot  pass  spontaneouslj^  from 
one  host  to  another.  Examples,  larvae  of  botflies,  Linguatula,  helmin- 
thes. 

Erratic  Parasites  are  those  which  in  their  adult  state  may  pass 
readily  from  one  host  to  another  of  the  same  or  different  and  widely 
separated  species.    Examples,  mosquitoes,  biting  flies,  ticks,  leeches. 

Determinate  Erratic  Parasites  are  those  which  may  pass  from  one 
host  to  another  of  the  same  species,  or  a  species  closely  allied  to  the  one 
abandoned.    Examples,  lice,  psoric  Acarina. 

Monoxenous  Parasites  are  (a)  those  the  eggs  of  which  are  expelled 
by  the  host,  the  embryos,  while  still  within  the  eggs,  passing  to  a  new 
host  where  hatching  and  development  to  the  adult  occurs.  Example, 
Ascaris. 

(b)  The  eggs  having  been  hatched,  the  larvae  are  noiu'ished  in  suitable 
conditions  of  moisture  and  temperature,  but  cannot  imdergo  further 
development  until  they  have  reached  the  body  of  their  host.  Example, 
Hemonchus  contortus. 

Heteroxenous  Parasites  are  (a)  those  which  pass  to  their  definitive 
host  by  an  intermediate  or  transitory  host,  in  which  they  cannot  attain 
their  complete  development;  consequently,  a  reciprocal  transmission 
between  these  hosts  is  essential  to  the  development  and  propagation  of 
the  parasite.    Examples,  tapeworms,  Plasmodium  of  malaria. 

(b)  The  eggs  of  the  parasite  are  hatched  in  the  Ijody  of  the  host,  the 
embryos  invading  the  tissues  of  the  same  individual  host  and  not  at^ 
taining  the  adult  state  until  they  have  reached  a  second  host.  Example, 
Trich ineUa  sp ira lis. 

Transmigration  is  a  term  applied  to  the  passing  of  heteroxenous 
parasites  from  one  host  to  another. 

Incidental  or  Stray  Parasites  are  those  which  under  natural  condi- 
tions are  occasionally  found  in  unusual  hosts.     Examples,  Gigantorhyn- 


FORMS  OF  PARASITISM  9 

chus  hirudinaceiis  (specific  in  pig,  incidental  in  man) ;  Fasciola  hepatica 
(specific  in  Her])ivora,  incidental  in  man). 

Ectoparasites  (Epizoa)  are  those  which  are  parasitic  to  the  surface 
of  the  body,  whether  burrowing  into  the  integument,  living  upon  it,  or 
only  occasional  visitors.  Examples,  scab  mites,  ticks,  and  other  Acarina, 
lice,  flies.    All  of  the  arthropodal  parasites  with  scarcely  an  exception. 

Endoparasites  (Entozoa)  are  parasites  which  enter  the  body  of  their 
host,  inhabiting  its  alimentary  canal,  blood,  and  other  tissues.  Exam- 
ples, Linguatula,  larvae  of  the  botflies,  and  almost  all  of  the  helminths. 

Helminthes  is  a  term  under  which  are  grouped  all  of  the  worms 
generally  jiarasitic,  with  the  exception  of  a  small  number  in  which  the 
body  is  annulated.  The  group  is  not  a  natural  zoological  one  and  is 
used  mostly  in  parasitology. 

In  terms  used  to  designate  parasitic  diseases  it  is  customary  to  apply 
the  name  of  the  genus,  or  other  group  name  to  which  the  parasite  be- 
longs, as  the  root,  to  which  is  added  the  suffix  asis  or  osis.  As  for  ex- 
ample : 

Pediculosis,  the  condition  produced  l)y  the  presence  of  lice  upon 
the  skin;  Acariasis,  the  condition  produced  by  the  presence  upon  the 
skin  of  mites  and  other  Acarina;  Filariasis,  the  condition  produced  by 
Filaria.  And  thus  we  have  Ascariasis  from  Ascaris,  Oxyuriasis  from 
Oxyuris,  Strongylosis  from  Strongylidae,  Trichinosis  from  Trichinella, 
Taeniasis  from  Tseniidae,  Fascioliasis  from  Fasciola,  Helminthiasis  from 
Helminthes,  and  Trypanosomiasis  from  Trypanosoma. 

In  view  of  the  many  factors  to  be  considered,  the  formulation  of 
exact  and  limiting  interpretations  of  terms  bearing  upon  kinds  of  par- 
asitism is  scarceh^  possible.  It  cannot  be  claimed  for  the  above  series, 
therefore,  that  it  is  entirely  satisfactory  as  stated  and  defined.  For  our 
conceptions  we  must  rely  upon  the  ])ehavior  of  the  typical  rather  than 
the  isolated  or  synthetic,  and  be  content  to  regard  anj^  grouping  based 
upon  modes  of  parasitism  as  more  convenient  than  exact.  It  is  difficult 
to  circumscribe  parasitism ;  while  we  speak  of  the  parasitic  mode  of  life 
as  a  form  of  symbiosis,  it  may  well  be  questioned  whether  such  insects  as 
mosquitoes  and  biting  flies  bear  a  true  sjanbiotic  relationship  to  their 
hosts;  their  fleeting  visits  certainly  do  not  constitute  the  living  together 
as  usually  implied  by  the  term.  Again,  we  may  not  be  able  to  draw  a 
distinct  fine  between  certain  predaceous  and  certain  parasitic  forms. 
From  the  more  general  viewpoint,  however,  it  may  be  repeated  that  all 
predaceous  animals  voluntarily,  by  the  exercise  of  their  powers  of  stealth 
and  cunning,  seize  upon  and  aim  to  destroy  their  prey  at  once,  feeding 
upon  the  body.  There  are  parasites  which  use  a  degree  of  stealth  in 
approaching  their  victims,  as  certain  parasitic  Diptera,  though  the 
invasion  of  the  body  of  its  victim  by  the  parasite  is  more  often  passive 
than  voluntaiy.     While  the  parasite  may  appropriate  a  share  of  the 


10  PARASITES  OF  THE  DOMESTIC  ANIMALS 

nutriment  of  its  host  or  feed  upon  its  host's  tissues,  it  is  detrimental  to 
the  parasite's  welfare  to  destroy  its  host.  To  destroy  the  body  of  the 
animal  harboring  it  would  mean  the  sacrifice  of  the  parasite's  means  of 
subsistence  as  well  as  in  most  cases  its  shelter.  When  the  host  animal 
dies  its  internal  parasites  die  with  it,  and,  if  it  were  not  for  the  previously 
occurring  transmission  of  their  offspring  to  new  hosts,  the  species  would 
rapidly  perish.  Serious  disturbance  or  death  of  the  host  due  to  its 
parasites  is  usually  brought  about  by  their  presence  in  large  numbers, 
in  which  case  there  is  the  operation  of  numerous  pathogenic  factors. 
A  fatal  termination  may  follow  rapidly,  but  more  often  there  are  afebrile 
morbid  phenomena  running  a  prolonged  course.  In  no  case  is  the  victim 
at  once  destroyed  and  wholly  or  in  part  devoured. 

The  parasite  is  always  smaller  and  weaker  than  its  host,  and  in  many 
cases  its  influence  upon  the  latter  is  not  observable.  It  may  be  said  in 
general  that  the  degree  of  injury  will  depend  upon  the  following  prin- 
cipal factors: 

Influence  Upon  the  Host 

1.  The  Number  of  Parasites  Present. — ^A  tapeworm  or  one  or  two 
ascarids  in  the  intestines  may  not  produce  a  noticeable  effect  upon  the 
host.  If  these  parasites  are  numerous  there  may  be  serious  disturbances 
in  the  host  resulting  from  the  deprivation  of  nutriment  which  has  been 
appropriated  by  the  infesting  worms,  from  the  toxins  which  they  elab- 
orate, or  a  more  acute  effect  may  be  brought  about  through  obstruction 
of  the  bowel  by  large  numbers  of  the  parasites  in  mass. 
*  2.  Their  Location. — An  encysted  larva  of  the  beef  or  pork  tapeworm 
in  its  usual  location  will  do  no  observable  harm  to  its  host,  but  if  it 
should  lodge  in  the  eye  or  central  nervous  system  it  might  give  rise  to 
serious  disorders.  As  a  rule,  intestinal  parasites  are  less  harmful  than 
those  which  invade  the  blood  or  respiratory  tract,  while  of  the  external 
parasites,  those  which  burrow  into  the  integument  are  more  injurious 
than  those  living  upon  the  surface. 

3.  The  Nature  of  their  Food. — Any  parasite  which  feeds  upon  the 
tissues  of  its  host  is  more  harmful  than  one  which  merely  appropriates 
a  share  of  the  latter's  ingested  nutriment.  The  blood-sucking  worms, 
when  present  in  considerable  numbers,  bring  about  serious  depletive 
disturbances,  while  such  worms  as  the  adult  ascarids,  nourishing  mainly 
upon  the  residue  of  food  materials,  are,  in  general,  less  harmful.  Sucking 
lice,  armed  with  piercing  mouth  parts,  are  more  disturbing  to  the  animal 
harboring  them  than  the  biting  lice  which  feed  upon  cutaneous  debris 
and  the  products  of  their  irritation. 

4.  Their  Movements. — Serious  pathologic  conditions  may  be 
brought  about  by  the  migrations  of  parasites  or  their  change  from  a 
usual   to   an   unusual   position.     Muscular  trichinosis,   the   collective 


INFLUENCE  UPON  THE  HOST  11 

effect  of  the  movement  of  myriads  of  embryos  of  Trichinella  spiralis,  is  a 
typical  instance.  An  otherwise  relatively  harmless  parasite  may  work 
its  way  into  a  duct,  or,  findmg  lodgment  in  an  unusual  organ,  set  up 
inflannnatory  changes  and  abscess  formation.  Again,  by  verminous 
wandering,  fistulous  connnunications  may  be  established  between 
contiguous  organs  normally  possessing  no  direct  connection. 

5.  Age  of  Host. — Young  animals  are  predisposed  to  endoparasitic 
invasion.  To  forms  which  penetrate  or  are  more  or  less  migratory,  the 
more  tender  tissues  of  the  young  offer  less  resistance  than  in  older 
animals.  Verminous  broiichitis  is  a  form  of  strongylosis  observed  almost 
exclusively  in  animals  which  are  immature.  The  reduced  vitalitj-  of 
old  age  invites  the  invasion  of  both  external  and  internal  parasites; 
there  is  not  only  a  lessened  ability  to  defend  from  attack,  but  reduced 
activities  and  secretions  of  the  intestines,  skin,  and  other  organs  de- 
crease the  capability  of  eliminating  either  ecto-  or  entozoa. 

Such  external  parasites  as  mosquitoes,  flies,  ticks,  and  bedbugs  are  of 
greatest  pathologic  importance  as  disseminators  of  infectious  diseases, 
acting  either  as  direct  carriers  or  as  intermediate  or  definitive  hosts  of 
the  infecting  organism.  Malaria,  Texas  fever,  and  forms  of  trypan- 
osomiasis are  among  diseases  which  are  known  to  be  spread  only  b}'  this 
means,  while  the  possibilities  as  carriers  of  typhoid  and  other  malignant 
infections  engendered  by  the  habits  of  the  connnon  house  fly  are  well 
known. 

That  Helminthes  elaborate  materials  toxic  to  their  host  has  been 
demonstrated  in  experiments  mth  the  isolated  poisons.  It  is  obvious 
that,  in  cases  of  heavy  infestation  especially,  this  toxic  effect  must  be 
considerably  contributed  to  by  the  products  of  decomposition  of  dead 
worms. 

Etiology. — So  varied  are  the  conditions  that  surround  the  propaga- 
tion and  existence  of  parasites  that  the  consideration  of  the  causes  of 
parasitic  diseases  is  best  embodied  in  chapters  devoted  to  their  particular 
occurrence.  However,  certain  circumstances  favoring  parasitism  may 
be  here  briefl}'  considered. 

Crowded  and  miclean  housing  favors  the  propagation  and  spread  of 
parasites  of  both  man  and  domestic  animals.  For  this  reason  lice  and 
scab  mites  find  their  most  favorable  season  in  the  winter  months,  when 
their  transmission  from  animal  to  animal  is  facilitated  and  the  reduced 
activities  of  the  skin  offer  less  resistance  to  their  invasion.  Pediculosis 
and  the  scab  acariases  are  seldom  seen,  however,  in  stables  that  are 
well  kept,  or  among  animals  where  due  attention  is  paid  to  cleanliness  of 
the  skin.  The  sunnner,  on  the  other  hand,  is  the  season  of  attack  by 
adult  parasitic  Diptera,  and  it  is  during  the  months  at  pasture  that 
ticks  most  rapidly  propagate  and  crawl  upon  their  hosts. 

In  helminthiasis  the  influences  of  environment  as  an  etiologic  factor 


12  PARASITES  OF  THE  DOMESTIC  ANIMALS 

are  more  subordinate  to  the  mode  of  development  of  the  infecting 
species.  Sheep  grazing  upon  low,  marshy  land  and  in  the  vicinity  of 
ponds  are  more  exposed  to  infestation  with  flukes,  because  there  are 
present  conditions  essential  to  the  molluscan  intermediate  host  in  which 
the  fluke  at  the  stage  of  the  miracidium  must  find  lodgment.  Infestation 
of  the  pig  or  the  ox  with  the  larvae  of  the  tapeworms  of  man  is  most 
likely  to  occur  where  untreated  human  excrement  is  used  as  a  fertilizer, 
or  where  their  food  may  otherwise  be  directly  or  indirectly  contaminated 
with  such  material,  while  invasion  of  the  human  host  with  the  adult 
worm  only  occurs  after  ingestion  of  the  tissues  of  the  larval  host.  The 
majority  of  ova  of  worms  expelled  by  the  host  fail  to  find  a  new  host,  or 
meet  with  unfavorable  conditions  and  are  lost.  Some,  as  those  of 
ascarids,  are  very  resistant  and  may  find  their  proper  host  after  months 
of  exposure  to  destructive  influences.  Migration  is  facilitated  to  some 
extent  where  hatching  takes  place  with  the  laying  of  the  egg,  as  in  the 
strongyles  of  the  respiratory  tract  and  in  Trichinella. 

While  much  remains  to  be  determined  as  to  the  life  histories  of  many 
of  the  internal  parasites,  clinical  experience  indicates  that  low  and  wet 
pasturage,  with  access  to  stagnant  collections  of  water,  is  a  strong 
etiologic  factor  in  helminthiasis,  either  as  harboring  possible  aquatic 
intermediate  hosts  of  the  worms,  or  as  a  vehicle  which,  directly  or  by 
drainage,  spreads  infestation  by  dissemination  of  their  germs. 


CHAPTER  III 

PHYLUM    I.  ARTHROPODA 

While  there  are  advantages  in  arranging  a  description  of  parasites 
according  to  their  location,  as  those  of  the  skin,  those  of  the  intestines, 
those  of  the  liver,  those  of  the  circulation,  etc.,  the  fact  that  so  many 
in  their  life  histories  pass  certain  stages  in  different  organs  and  different 
species  of  hosts  makes  such  an  arrangement  somewhat  confused.  It 
seems  better,  therefore,  to  treat  of  the  natural  history  of  each  parasite 
in  the  parasite's  order,  essentially  including  such  anatomical  and  zoolog- 
ical migrations  as  may  be  involved,  while  at  the  same  time  considering 
its  pathogenic  influences  in  these  varying  locations. 

Aside  from  the  phytoparasites,  which  are  not  included  in  this  work, 
the  parasites  infesting  man  and  domestic  animals  are  distrilnited  among 
four  grand  divisions  or  phyla  of  the  animal  kingdom,  which,  in  the  order 
of  their  zoological  grade,  are  Protozoa,  Platyhelminthes,  Coelhelminthes, 
and  Arthropoda.  The  last  named  group  contains  most  all  of  the  external 
parasites  and  is  the  first  to  be  considered  in  the  pages  to  follow. 

As  a  foundation  for  the  scientific  control  of  parasitism  and  for  the 
recognition  of  adaptations  to  its  various  forms,  at  least  an  elementary 
knowledge  of  the  structure  and  habits  peculiar  to  the  phylum  and  its 
subdivisions  to  which  the  parasite  belongs  is  of  essential  importance. 
Only  the  more  prominent  structural  features  upon  which  the  separation 
of  the  different  groups  and  their  subgroups  is  based  will  be  given  here. 
For  more  detailed  study  the  student  is  referred  to  an  advanced  text-l:)Ook 
in  zoology. 

The  phylum  Arthropoda  includes  such  animals  as  the  craj^fish,  crabs, 
lobsters,  spiders,  centipedes,  and  insects.  The  body  is  provided  with  a 
hard  or  leathery  external  chitinous  skeleton  divided  into  a  number  of 
segments  demarcated  externally  by  constrictions,  each  segment  in  the 
adult,  or  a  certain  number  of  the  segments,  bearing  jointed  appendages 
(Fig.  1).  There  are  usually  two  or  more  body  regions  distinguished  by  a 
special  modification  of  the  constituant  segments.  In  order  that  move- 
ments may  take  place  between  the  segments  of  both  the  body  proper 
and  of  the  appendages,  the  cuticle  at  these  points  is  thin  and  delicate 
(Fig.  9),  forming  joints  which  are  protected  by  an  overlapping  of  the 
heavier  chitinous  armor. 

All  arthropods  periodically  molt,  the  process  consisting  of  the  break- 
ing and  casting  off  of  the  chitinous  cuticle  after  it  has  loosened  from  the 


U  PARASITES  OF  THE  DOMESTIC  ANIMALS 

underlying  tissue  and  a  new  cuticle  has  been  formed.  While  the  cuticle 
is  at  first  thin  and  soft,  later  it  becomes  hard  and  unyielding,  therefore 
the  moltings  are  necessar}-  for  the  accommodation  of  growth  and  occur 
periodically  as  long  as  this  growth  continues.  Chitin,  to  which  the 
firmness  of  the  cuticular  exoskeleton  is  due,  is  an  organic  substance  in 
which  lime  salts  may  be  deposited,  as  occurs  in  the  Crustacea.  The 
skin  is  never  ciliated,  nor  do  ciliated  cells  occur  in  any  other  organs  of 
the  body. 

The  musculature  (Fig.  9)  consists  of  a  large  number  of  separate 
muscles  passing  from  one  segment  to  another  and  attached  at  their 
extremities  to  the  mner  side  of  the  skin,  their  contraction  bringing  about 
movements  of  the  segments  of  the  body  and  appendages  one  upon  the 
other.  They  may  be  attached  by  so-called  tendons,  which  consist  of 
invaginations  of  the  cuticle  surrounded  by  a  corresponding  invagination 
of  the  epidermis.    The  muscle  fibers  are  striated  and  multinuclear. 

The  digestive  tract  (Fig.  2)  passes  directly,  or  with  little  flexion, 
through  the  bodj^,  the  mouth  being  at  the  anterior  end  and  usually 
ventral,  the  anus  posterior.  Accessory  organs,  as  salivary  glands  and 
liver,  may  or  may  not  be  present. 

Of  the  circulatory  system  (Figs.  2  and  3)  the  most  constant  portion  is 
the  heart,  which  is  usually  tubular  and  located  dorsally.  On  each  side  of 
the  organ  are  openings  provided  with  valves  through  which  the  blood 
passes  to  be  propelled  forward.  From  the  large  arteries  the  blood  may 
pass  directly  into  blood  sinuses,  or  it  may  course  through  capillaries  and 
veins,  though  the  vascular  system  is  never  entirely  closed.  The  blood  is 
usualty  a  colorless  fluid  with  colorless  amoeboid  corpuscles. 

In  aquatic  forms  (Crustacea)  respiration  is  b}'  gills,  while  in  the  air- 
breathers  it  may  be  by  tracheae  (Figs.  5  and  6),  consisting  of  tubular 
ramifications  from  without  to  within  the  body,  or  by  peculiar  infolding 
modifications  of  the  integument  functioning  as  lungs.  In  some  of  the 
lower  forms  respiratory  organs  are  entirely  absent,  the  function  in  such 
cases  being  diffused  over  the  entire  body  surface. 

In  various  spaces  within  the  bodies  of  Arthropoda  are  frequently 
found  fat  bodies,  a  connective  tissue  the  cells  of  which,  richly  laden  with 
fat,  serve  as  a  store  of  nourishment.  The  fact  that  products  of  tissue 
metabolism,  such  as  uric  acid,  have  been  found  m  the  fat  body,  leads  to 
the  conclusion  that  it  also  acts  as  a  place  of  storage  for  substances  of 
excretion  before  their  elimination  by  the  excretory  organs,  which  latter 
greatly  vary  in  the  different  groups.  In  insects  and  arachnids  these 
organs  are  represented  by  the  Malpighian  tubes,  long  glandular  canals 
which  open  into  the  posterior  portion  of  the  digestive  tract. 

The  nervous  system  consists  typically  of  a  ventral  chain  of  ganglia 
connected  by  a  double  longitudinal  nerve  cord.  In  well-developed  seg- 
ments the  ganglia  are  large,  and  a  pair  of  ganglia  to  each  segment  might 


ARTHROPODA  15 

be  expected,  as  in  the  annelid  worms.  In  the  Arthropoda,  however, 
there  are  differences  due  to  fusion  of  the  segments,  in  which  case  there 
is  also  fusion  of  their  ganglia.  Such  fusion  is  usually  accompanied  by 
more  or  less  shortening  of  the  body,  an  example  of  which  is  afforded  b}^ 
the  spiders  and  crabs  where  the  whole  ventral  chain  unites  in  a  single 
ganglionic  mass.  From  the  most  anterior  of  the  ventral  ganglia  there 
spring  two  nerve  cords  which  pass  on  either  side  of  the  esophagus  to 
unite  above  it  with  the  paired  cerebral  ganglion  or  brain,  Ijong  in  the 
head.  This  ganglion  remains  distinct,  its  dorsal  position  preventing  its 
fusion  with  ganglia  of  the  ventral  chain. 

Of  the  sense  organs  the  most  highly  developed  are  the  eyes,  which  are 
compound  (Fig.  6),  or  appear  as  simple  ocelli.  In  many  arthropods 
there  are  both  of  these  forms,  while  others  are  provided  only  with  ocelli, 
and  in  some  arthropods  eyes  are  absent.  In  the  compound  eyes  the 
cuticle  covering  them  is  divided  into  hexagonal  facets,  the  number  of 
which  varies  with  different  groups  from  a  dozen  to  two  thousand  or 
more,  each  of  these  areas  corresponding  to  a  small  chitinous  lens.  The 
compound  eyes  are  two  in  number,  while  the  number  of  oceUi  varies. 
The  latter  are  very  small  and  have  their  highest  development  in  the 
spiders. 

With  rare  exceptions  the  sexes  are  separate,  and  reproduction  is 
generall.y  by  fertilized  eggs,  though  parthenogenesis  occurs,  in  some 
cases  having  a  certain  relationship  to  the  life  history.  Usually  the  sexes 
can  be  readily  distinguished  by  the  difference  in  size  and  by  various 
modifications  of  the  appendages. 

Of  the  subgroups  of  the  phylum  Arthropoda  only  those  containing 
parasitic  species  of  medical  interest  will  be  considered  in  this  work. 
These  are  included  in  the  two  classes  Insecta  and  Arachnida,  which, 
with  scarceh'  an  exception,  contain  all  of  the  external  parasites.  It  is 
not  correct,  however,  to  say  that  the  arthropodal  parasites  are  exclusively 
external,  as  certain  insects  and  arachnids  pass  a  phase  of  their  develop- 
ment within  the  bodies  of  their  hosts. 

Class  I.    Insecta 

Arthropoda  (p.  13). — In  number  of  species  the  insects  constitute 
the  largest  of  all  animal  groups.  The  body  is  essentially  segmented,  and 
is  di\'ided  into  three  regions, — head,  thorax,  and  abdomen,  which  are 
distinctly  marked  off  from  each  other  (Fig.  1). 

The  head  is  usuall}-  freely  movable  at  its  jmiction  with  the  thorax, 
and  typically  bears  on  each  side  a  compoimd  eye  (Figs.  1  and  7),  be- 
tween which  there  may  be  a  varying  number  of  simple  ocelli. 

Arising  from  the  head  are  a  pair  of  antennae  which  consist  of  seg- 
ments varying  in  size,  shape,  and  number  according  to  species. 


16 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


The  mouth  parts  (Fig.  4)  undergo  great  modification,  though  all  may 
be  referred  to  a  common  type.     This  is  well  presented  in  its  primitive 

condition  by  the  grasshopper, 
in  which  we  have  the  labrum, 
or  upper  lip,  represented  b}'  a 
broad  unpaired  plate  situated 
in  front  of  the  mouth.  Under 
the  labrum  is  a  parr  of  strong- 
jaws,  the  mandibles,  each  con- 
sisting of  a  single  unsegmented 
piece  with  a  cutting  innei'  edge, 
the  two  having  a  lateral  move- 
ment. Following  the  mandibles 
is  the  first  pair  of  maxillae  which 
are  prehensile  and  gustatory  in 
function.  These  have  a  num- 
ber of  joints  and  bear  curved 
and  segmented  palpi.  The  sec- 
ond pair  of  maxillae  are  fused 
to  form  a  single  plate, — the  la- 
bium, which  is  accessory  in  func- 
tion to  the  first  pair  of  max- 
illae, and,  like  the  latter,  bear  a 
pair  of  segmented  palpi.  The 
labium  forms  the  posterior  and 
the  labrum  the  anterior  bound- 
ary of  the  mouth. 

The  thorax  (Fig.  1)  has  three 
a  middle, — the.  mesothorax, 


Fig.  1. — Diagram  of  an  Insect,  with  Head  and 
Thoracic  Segments  Disarticulated:  a,  head, 
bearing  compound  eyes,  simple  ocelli,  and 
antennae;  b,  prothorax;  c,  mesothorax;  d,  meta- 
thorax;  e,  abdomen;  f,  ovipositor.  The  pro-, 
meso-,  and  metathorax  each  bear  a  pair  of  legs; 
the  meso-  and  metathorax  each  a  pair  of  wings. 
1,  Coxa;  2,  trochanter;  3,  femur;  4,  tibia;  .5,  tar- 
sus, terminating  in  a  claw  (after  Orton,  by 
Dodge;  Copyright,  1894,  by  Harper  &  Brothers). 

segments,   an  anterior, — the   prothorax 


Fig.  2. — Diagram  of  the  Principal  Internal  Anatomical  Parts  of  an 
Insect:  m,  mouth;  or,  crop;  st,  stomach;  i,  lower  portion  of  intestine; 
a,  anus;  h,  heart;  s,  salivary  glands;  c,  cerebral  ganglion;  n,  ventral 
ganglion;  Mp,  Malpighian  tulDules;  o,  ovaries;  g,  genital  aperature  (after 
Boas,  by  Kirkaldy  &  Pollard). 


and  a  posterior, — the  metathorax. 
somewhat  fused. 


The  last  two  of  these  are  usuallv 


ARTHROPODA 


17 


There  are  three  pairs  of  legs,  each  thoracic  segment  l^earing  one  pair 
(Fig.  1).    The  leg  is  divided  into  five  articulated  parts, — coxa,  trochanter, 
femur,  tibia,  and  tarsus.    The  attachment   to 
the  bod}'  is  by  the  short  coxa,  to  which  is  joined        4, 
the  trochanter  which  is  also  short.     Following    •'^Cr^<f7^'~>r~>''~^ 
the  trochanter  are  two  long  segments, — the  fe-         v  ^ 

mur  and  tibia,  the  former  considerably  thicker      fig.  3.— Diagram  of  In- 
than  the  latter  and  contaming  the  muscles.    The  sect's  Heart:  c,  constriction 

tarsus,  or  foot,  follows  the  tibia,  and  consists  of    between   two    chambers;    V, 
',  „      ,  ,       ,  ,  •  valves  (after  Boas,  bj'  Kirk- 

a  number  ot  short  segments,  the  last  bearmg  aidy  &  Pollard), 
hook-like  structures,  or  claws. 

Usualh'  there  are  two  pairs  of  wiiigs  arising  dorsally  from  the  meso- 


FiG.  4. — Mouth-parts  of  Locust,  a  biting  insect:  Labruni,  or  upper-lip, 
above,  on  each  side  of  which  are  the  mandibles,  or  upper  pair  of  jaws. 
Labium,  or  under  lip,  with  labial  palpi  below.  Ma.xillae,  or  lower  pair  of 
jaws,  with  maxillary  palpi,  to  right  and  left  (from  photomicrograph  of 
mounted  specimen,  by  Hoedt). 

and  metathorax  (Fig.  1).    They  consist,  when  fully  developed,  of  two 
closely  apposed  chitinous  outgrowths,  between  which  are  extensions  of 


18 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


the  blood  sinuses  and  tracheae.  Sometmies  the  anterior,  sometimes  the 
posterior  pair  is  the  larger,  and  both  may  be  flexible  and  adapted  for 
flight.  In  some  insects  (beetles)  the  anterior  pair  is  modified  to  form 
wing-shields,  or  elytra,  which  are  hard,  but 
slightly  flexible,  structures  serving  to  cover 
and  protect  the  posterior  wings  during  rest. 
Some  insects  possess  but  one  pair  of  wings 
(dipterous),  while  in  others  wings  are  entirely 
absent  (apterous). 

The  abdomen  is  segmented,  the  number  of 
segments  varying  with  different  groups.  Each 
segment  consists  of  two  cuticular  plates  (Fig.  6), 
the  dorsal  tergite  and  the  ventral  sternite, 
which  are  united  laterally  by  a  softer  mem- 
brane, the  pleurite.  There  are  no  abdominal 
limbs  or  limb-like  appendages. 

Respiration  is  by  tracheae  (Fig.  5),  a  system 
of  tubes  containing  air.  These  communicate 
with  the  outside  by 
the  spiracles  (Fig. 
6),  small  s>anmet- 
r  i  c  a  1 1  y  disposed 
openings  located 
laterally,  one  pair 
on  the  meso-  and 
one  pair  on  the 
metathorax  and  a 
pair  on  each  of  the 
abdominal  segments 
except  the  most  posterior.  Just  inside  of  the  spiracles  the  tracheae  are 
usually  united  by  longitudinal  trunks  from  which  are  given  off  fine 
branches  which  ramify  and  anastomose  within  the  body.  Respiration 
is  effected  by  abdominal  movements  of  contraction  and  expansion. 

Insects  are  mostly  oviparous.  In  some  the  developed  embryo  is 
released  from  the  egg  while  still  within  the  body  of  the  parent,  or  this 
may  occur  just  as  the  egg  is  extruded.  There  are  also  pupiparous  forms 
where  the  young  pass  from  the  body  of  the  female  ready  to  enter  the 
pupal  stage  in  their  development. 

In  order  that  the  newly  hatched  larvae  may  be  supplied  with  nourish- 
ment, the  eggs  are  generally  deposited  where  suitable  food  is  present. 
In  many  insects  oviposition  occurs  by  means  of  an  ovipositor,  a  tube- 
like organ  which  is  developed  from  the  posterior  abdominal  segments 
and  which  may  project  free  from  the  body  or  may  be  retracted  into  it. 
In  the  Hjmienoptera  the  ovipositor  may  be  modified  to  serve  as  a  sting, 


Fig.  5. — Diagram  show- 
ing the  chief  trunks  of  the 
tracheal  system  of  an  in- 
sect (after  Boas,  by  Kirk- 
aldy  &  Pollard). 


Fig  .  6. — Abdomen  of  Lo- 
cust,s  howing  Spiracles  1,  2,13, 
4,  5,  6,  7  and  8,  one  on  each  side 
of  each  of  the  abdominal  seg- 
ments; A,  auditory  sac  (drawn 
in  part  from  Packard's  Zool- 
ogy). 


ARTHROPODA 


19 


Fig.  7. — Head  of 
the  bee,  showing 
compound  eyes,  the 
three  ocelH,  and  the 
antennae.  —  Magni- 
fied (after  Orton,  by 
Dodge;  Copyright, 
1894,  by  Harper  & 
Brothers) . 


a  weapon  of  defense  provided  with  poison  glands.    From  its  nature  the 
sting  is  essentially  onh'  possessed  by  the  females. 

Some  insects  on  leaving  the  egg  develop  directly  to  the  adult  stage, 
the  larva  in  most  cases  differing  from  the  adult  prin- 
cipalh'  in  the  absence  of  wings.  In  such  cases  there 
is  a  slight  change  of  form  with  successive  molts, 
the  wings  being  ultimateh'  acquired.  Here  the  meta- 
morphic  process  is  not  thorough,  and  is  therefore 
referred  to  as  mcomplete  metamorphosis.  The  ma- 
jorit}^  of  insects  when  hatched  from  the  egg  bear 
no  resemblance  to  the  adult,  and  there  is  no  observ- 
able gradual  approach  to  this  form.  The  larva  is 
characteristically  worm-like  and  an  active  and  vora- 
cious feeder,  a  number  of  molts  occurring  with  the 
increase  in  size  during  this  stage.  There  then 
intervenes  between  the  larval  and  adult  stages  a 
period  of  pupation,  during  which  the  animal  is  quies- 
cent and  a  series  of  changes 

occur  in  the  body.    At  the 

conclusion  of  these  changes  the  pupal   case 

splits  and  the  imago  emerges,  which,  with 

the  unfolding  of  the  ap- 
pendages and  hardening 

of  the  cuticle,  has  in  all 

essentials  developed  into 

the      complete      sexual 

adult.      In    this    form 

of      development      the 

changes  are  distinct,  and 

the  process  is  referred 

to    as    complete    meta- 
morphosis (Fig.  8). 
The   duration  of  life 

in  insects,  including  the 

stages  of  the  egg,  larva, 

pupa,  and  adult,  usually 

does  not  extend  bej^ond 

a  year.     With  quite  a 

number      it     is     much 

shorter  than  this,  while 

with  others  it  maj'  be  a 

matter  of  several  years, 

an  extreme  example  of 

larval    longevity   being 


Fig.  9. — Diagram  of  termi- 
nal segments  of  arthropod  leg, 
with  muscles,  a,  articulation; 
f,  flexors;  e,  extensors  Cafter 
Boas,  by  Kirkaldy  &  Pollard). 


Fig.  8.  —  Metamor- 
phosis of  the  House  Fly, 
showing  oval,  larval, 
pupal,  and  adult  stages. 
On  the  right  is  an  en- 
largement of  the  foot; 
on  the  left,  the  foot  pad, 
showing  sticky,  glandu- 
lar hairs;  on  upper  left, 
a  tsetse  fly  (from  photo- 
graph of  drawing  by 
author). 


20  PARASITES  OF  THE  DOMESTIC  ANIMALS 

afforded  by  the  seventeen-year  cicada.  Most  of  the  insect  Hfe  is  occupied 
bj'  the  larval  stage,  during  which  the  greatest  growth  takes  place.  With 
a  few  exceptions,  as  honey  bees  and  ants,  the  period  of  the  adult  is  short, 
in  some  cases  a  few  daj^s  or  even  hours.  The  life  of  the  adult  is  de- 
voted to  the  activities  concerned  in  reproduction,  and  the  insect  usualh'' 
dies  when  this  is  accomplished. 

Of  the  class  Insecta  the  five  following  orders  contain  parasites  of 
medical  importance: 

Order      I.  Diptera — Flies,  gnats,  and  mosquitoes. 

Order    II.  Siphonaptera — Fleas. 

Order  III.  Siphunculata — Sucking  lice. 

Order  IV.  Mallophaga — Biting  lice. 

Order    V.  Hemiptera — Bedbugs  and  allies.  ^Vv^^s-a.^ 

Classification  of  Parasites  of  the  Class  Insecta 

Phylum  I.  Arthropoda.    P.  13. 
Class  A.  Insecta.    P.  15. 
Order  1.  Diptera.    P.  23. 

Family  (a)  Culicidse.    Mosquitoes.    P.  24. 
Genus  and  Species: 

Culex  pungens.    Pp.  25,  26. 
Anopheles  quadrimaculatus.    P.  26. 
A.  pmictipennis.    P.  28. 
Ades  calopus.    P.  29. 
Family  (b)  Simuliida?.    Buffalo  gnats.    P.  31. 
Genus  and  Species: 

Simulium  pecuarum.    Animals  attacked,  equines  and  cattle. 
P.  32. 
Family  (c)  Tabanidse.     Horseflies,  gadflies.     Animals  attacked, 
equines,  cattle.    P.  35. 
Genus  and  Species: 

Tabanus  atratus.    P.  35. 
T.  lineola.    P.  36. 
Family  (d)  Muscidse.    House  fly  and  allies.    P.  37. 
Genus  and  Species: 

Musca  domestica.     Injurious  to  man  and  domestic  animals 

by  irritation  and  contamination.    P.  37. 
Stomoxvs  calcitrans.    Animals  attacked,  equines  and  cattle. 

P.  39! 
Lyperosia  irritans.    Animals  attacked,  cattle.    P.  41. 
Glossina  palpalis.      Animals  attacked,  man,  and  domestic 

and  wild  animals.    P.  44. 
G.  morsitans.    Animals  attacked,  same.    P.  44. 
G.  longipalpis.    Animals  attacked,  same.    P.  44. 


ARTHROPODA  21 

Chiysomyia  macellaria.     Larvae  attack  flesh  and  mucous 

surfaces  of  man  and  lower  animals.    P.  50. 
Sarcophaga    sarraceniae.      Larvae    attack    fresh    meat    and 

wounds  of  animals.    P.  52. 
Calliphora  vomitoria.    Larvae  attack  fresh  and  decomposing 
meat  and  wounds.    P.  52. 
Family  (e)  Hippoboscidae.    P.  47. 
Genus  and  Species: 

Melophagus  ovinus.    Host,  sheep.    P.  47. 
Family  (f)  CEstrida?.    Botflies.    P.  53. 
Genus  and  Species: 

Gastrophilus  intestinalis.    Host,  equines.    P.  53. 
G.  hemorrhoidalis.    Host,  equines.    P.  57. 
G.  nasahs.    Host,  equines.    P.  57. 
Hypoderma  lineata.    Host,  cattle.    P.  57. 
H.  bovis.    Host,  cattle.    P.  58. 
CEstrus  ovis.    Host,  sheep.    P.  62. 
Order  2.  Siphonaptera.    P.  65. 

Family  (a)  Pulicida?.    Fleas.    P.  65. 
Genus  and  Species: 

Ctenocephalus  canis.    Host,  dog.    P.  65. 
C.  felis.    Host,  cat.    P.  65. 
Pulex  irritans.    Host,  man.    P.  65. 
Order  3.  Siphunculata.    Sucking  lice.    P.  70. 
Family  (a)  Pediculida^.    P.  70. 
Genus  and  Species: 

Haematopinus  asini.    Host,  equines.    P.  73. 
H.  eurysternus.    Host,  cattle.    P.  74. 
Linognathus  vituli.    Host,  cattle.    P.  74. 
L.  pedalis.    Host,  sheep.    P.  76. 
L.  stenopsis.    Host,  goat.    P.  77. 
Ha?matopinus  suis.    Host,  hog.    P.  77. 
Linognathus  piliferus.    Host,  dog.    P.  78. 
Pediculus  humanus.    Host,  man.    P.  79. 
P.  corporis.    Host,  man.    P.  79. 
Phthirius  pubis.    Host,  man.    P.  79. 
Order  4.  Mallophaga.    Biting  lice.    P.  7L 
Family  (a)  Philopterida?.    P.  71. 
Genus  and  Species: 

Trichodectes  equi.    Host,  equines.    P.  73. 

T.  pilosus.    Host,  equines.    P.  73. 

T.  scalaris.    Host,  cattle.    P.  75. 

T.  sphaerocephalus.    Host,  sheep.    P.  76. 

T.  chmax.    Host,  goat.    P.  77. 


22  PARASITES  OF  THE  DOMESTIC  ANIMALS 

T.  latus.    Host,  dog.    P.  78. 

T.  subrostratus.    Host,  cat.    P.  79. 

Goniocotes  gallinae.    Host,  chicken.    P.  82. 

G.  gigas.    Host,  chicken.    P.  82. 

Lipeurus  caponis.    Host,  chicken.    P.  83. 

L.  heterographus.    Host,  chicken.    P.  83. 

Goniodes  styhfer.    Host,  turkey.    P.  84. 

Lipeums  meleagridis.    Host,  turkey.    P.  84. 

Philopterus  icterodes.    Hosts,  ducks  and  geese.    P.  84. 

Lipeums  anatis.    Hosts,  ducks  and  geese.    P.  84. 

Philopterus  C3'gni.    Host,  swan.    P.  86. 

Ornithonomus  cygai.    Host,  swan.    P.  86. 

Goniocotes  compar.    Host,  pigeon.    P.  86. 

Goniodes  damicornis.    Host,  pigeon.    P.  86. 

Lipeurus  columbse.    Host,  pigeon.    P.  86. 
Family  (b)  Liotheidse.    P.  71. 
Genus  and  Species: 

Menopum  trigonocephalum.    Host,  chicken.    P.  83. 

M.  biseriatuni.    Host,  turkey.    P.  83. 

Trinotum  luridum.    Hosts,  ducks  and  geese.    P.  84. 

T.  lituratuni.    Hosts,  ducks  and  geese.    P.  86. 
Order  5.  Hemiptera.    P.  89. 
Family  (a)  Cimicidse.    P.  90. 
Genus  and  Species: 

Cimex  lectularius.    Hosts,  man,  poultry,  etc.    P.  90. 


CHAPTER  IV 

MOSQUITOES   AND   (iXATS 

Order  I.  Diptera. — Insecta  (p.  15).  The  dipterous  insects  have  only 
the  anterior  pair  of  wings  developed,  the  posterior  pair  being  repre- 
sented b}'  rudimentary  structures  called  halteres,  or  balancers,  which 
are  supposed  to  function  as  organs  of  balance.  In  some  parasitic  forms 
(sheep  '4ick,"  bat  fly)  wings  are  entireh'  wanting. 

The  head,  thorax,  and  abdomen  are  sharply  defined.  The  mouth 
parts  are  adapted  for  sucking,  the  haustellum,  or  sucking  tube,  being- 
formed  by  the  labium  and  labrum,  within  which  lie  the  mandibles  and 
maxillae,  which  may  be  modified  into  blade-like  structures  for  piercing. 
With  this  structure  the  insect  sucks  the  juices  of  plants  or  penetrates  the 
skin  of  animals  and  feeds  upon  their  blood.  In  the  flies  the  antennae  are 
short,  consisting  of  but  three  well-developed  joints.  The  three  thoracic 
segments  are  frequently  fused,  and  the  tarsi  have  five  segments. 

Metamorphosis  is  complete.  The  larvae  are  apodal  grubs,  maggots, 
or  wrigglers,  the  latter  aquatic  (mosquitoes). 

Parasitism. — The  dipterous  group  of  insects  includes  a  number  of 
species  varying  in  their  grade  of  parasitism  from  optional  occasional  to 
obligate  occasional  and  permanent.  They  are  chiefly  of  importance 
from  the  medical  viewpoint  as  carriers  of  bacterial  and  animal  parasitic 
infection,  investigations  within  recent  3'ears  well  establishing  the  fact 
that  certain  serious  and  often  fatal  diseases  of  man  and  domestic  animals 
are  spread  by  these  insects  either  as  essential  hosts  or  as  direct  carriers 
of  the  infectrtig  organism.  As  essential  hosts  a  part  of  the  development 
of  the  pathogenic  organism  must  essentially  be  undergone  in  the  insect. 
As  direct  carriers  they  may  inoculate  directly  into  the  blood  with  con- 
taminated piercing  or  biting  mouth  parts,  or  the}--  may  simply  trans- 
port disease  germs  upon  their  bodies  and  appendages,  contaminating 
wounds,  food,  or  any  object  upon  which  they  may  alight. 

As  blood-sucking  pests  and  sources  of  torment  in  the  habitations  of 
man  and  in  the  fields  and  stables  of  his  live  stock,  many  of  these  two- 
winged  insects  are  of  veiy  considerable  economic  as  well  as  pathologic 
importance.  In  view  of  all  that  at  the  present  time  can  be  charged 
lip  against  them,  the}'  are  well  worthy  of  the  increasing  attention  they 
are  recei\'ing  with  a  view  to  their  more  effectual  control. 

Of  the  families  of  the  order  Diptera  containing  parasitic  species,  six 
are  here  considered,  as  follows: 


24  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Family      I.  Culicidse — Mosquitoes. 
Family    II.  Simuliidse — Buffalo  gnats. 
Family  III.  Tabanidae — Horseflies. 
Family  IV.  Muscidae — House  fly  and  allies. 
Family    V.  Hippoboscidae — Sheep  "tick." 
Family  VI.  (Estridae— Botflies. 

Family  I.  Culicid^;  Mosquitoes 

Diptera  (p.  23). — The  mosquitoes  are  slender-bodied  Diptera  with 
narrow  wings  which  have  a  distinctive  fringe  of  scale-like  hair  upon 
their  margins,  and  in  most  cases  also  on  each  of  the  wing  veins.  In  the 
female  the  prol)oscis  is  long,  slender,  and  adapted  for  piercing.     The 


Fig.  10. — Egg-mass  of  Culex  pungens,  above;  young  larva,  greatly  enlarged,  at  right; 
young  larvae,  less  enlarged,  below;  enlarged  eggs  above  at  left  (after  Howard,  Bui.  No.  4, 
Bureau  of  Entomology,  Dept.  of  Agr.). 

males  do  not  suck  blood,  differing  from  the  females  in  the  absence  of 
the  piercing  stylets  and  in  the  possession  of  plumose  antennae. 

Mosquitoes  have  an  adaptation  to  a  very  wide  range,  flourishing 
equally  as  well  in  the  frigid  regions  of  the  Arctic  and  Antarctic  as  in  the 
humid  heat  of  the  tropics.  Until  comparatively  recent  years  few  species 
Avere  known,  but  more  intensive  study,  in  view  of  their  importance  as 
carriers  of  disease  and  as  pests  of  man,  has  brought  the  mosquito  fauna 
of  the  world  up  to  about  one  hundred  genera  including  seven  hundred 
species,  of  which  there  are  about  fifty  known  in  the  United  States. 

Breeding  Habits. — In  the  larval  stage  all  the  known  mosquitoes 
are  aquatic,  l^ut  such  differences  occur  in  their  life  histories  and  habits 


MOSQUITOES  AND  GNATS  25 

that  110  one  species  will  serve  as  typical  of  the  group.  In  observations 
conducted  by  L.  O.  Howard  at  Washington,  D.  C.  (1900  Rept.),  upon 
the  species  Cidex  pungens  it  was  determined  that  the  eggs  were  laid  upon 
the  water  surface  in  masses  of  a  variety  of  shapes,  often  described  as 
boat-shaped  because  a  common  form  is  that  of  a  pointed  ellipse  (Fig.  10). 
The  number  of  eggs  in  each  mass  varied  from  two  hundred  to  four  hun- 
dred, all  arranged  perpendicularl}'  and  in  longitudinal  rows.  The  in- 
dividual eggs  are  slender,  somewhat  pointed  at  the  tip,  and  at  the  bottom 
broader  and  blunt,  having  a  length  of  0.7  mm.  and  a  diameter  of 
0.16  mm.  at  the  base. 

It  has  been  demonstrated  that  under  the  advantageous  conditions 
of  the  warm  summer  months  eggs  may  hatch  in  less  than  a  day  from  the 
time  they  are  deposited.  The  larvae,  issumg  from  the 'under  side  of  the 
egg  mass,  are  elongate,  with  head,  thorax  and  alxlomen  distinct,  the 
head  bearing  prominent  antenna?  each  consisting  of  a  single  segment. 
About  the  mouth  is  a  mass  of  prehensile  filaments.  The  abdomen  is 
segmented,  and  respiration  is  by  tracheae  which  open  at  the  apex  by 
means  of  the  anal  siphon.  They  appear  to  undergo  four  molts,  and, 
under  favorable  conditions,  may  be  transformed  into  pupae  in  about 
seven  days.  Studied  at  a  period  when  the  larva  is  nearly  full  grown, 
it  is  seen  to  remain  near  the  surface  of  the  water  with  its  respiratory 
tube  at  the  exact  surface  and  its  mouth  below  receiving  food  which  is 
directed  to  it  by  the  rotary  movements  of  the  mouth  filaments.  Occa- 
sionly  the  larva  descends  below  the  surface,  but,  by  a  series  of  wrigglings, 
quickly  returns.  The  return  is  only  accomplished  by  considerable 
exertion,  as,  once  below  the  surface,  the  tendency  of  the  larva  is  to  sink 
rather  than  to  rise.  If,  therefore,  for  any  reason  it  is  unable  to  suffi- 
ciently exert  itself  to  again  reach  the  surface,  it  will  perish.  The  eflficacy 
of  the  film  of  oil  spread  upon  the  water  may  be  thus  explained;  it  not 
only  prevents  access  to  the  air,  but,  by  its  deleterious  effect,  renders  the 
larva  unable  to  exert  sufficient  muscular  force  to  recover  the  position 
necessary  for  respiration  and  buoyancy. 

The  transformation  to  the  pupal  stage,  occurring  under  favorable 
conditions  aljout  the  seventh  day,  is  marked  by  a  great  enlargement  of 
the  thoracic  segments  (Fig.  11).  Here  the  reverse  of  the  just  described 
physical  phenomena  obtains;  the  pupa  is  lighter  than  water,  and,  unlike 
the  larva,  effort  is  required  to  sink  rather  than  to  rise.  It  remains  mo- 
tionless at  the  surface,  when  disturbed  descending  to  the  bottom  by 
violent  wrigglings.  As  soon  as  these  exertions  cease  it  will  again  grad- 
ually rise.  The  differential  structure  of  the  pupa  is  noticeable  in  the 
tnlargement  of  the  thorax,  and  in  that  the  air  tubes  no  longer  open  at 
the  abdominal  apex,  but  through  two  ear-like  processes  on  the  thorax, 
the  pupa  remaining  ujiright  at  the  water's  surface  instead  of  head  down- 
ward as  in  the  larval  stage.     Since  the  adult  insect  emerges  from  its 


26 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


pupal  case  at  the  thorax,  there  is  an  apparent  adaptability  in  this  re- 
versal of  position. 

The  common  house  or  ''rain  barrel"  mosquito  of  the  Northern 
United  States,  Culex  pimgens  (Fig.  12),  breeds  throughout  the  summer, 
broods  developing  wherever  there  may  be  standmg  water,  as  in  pools, 
troughs,  cans,  discarded  bottles,  gutters,  etc.  The  adults  of  this  species 
may  pass  the  winter  in  the  shelter  of  darkened  retreats,  such  as  the 
cellars  of  houses,  behind  furniture,  outbuildings,  and  wood  piles, 
emerging  from  their  hibernation  in  the  spring  to  deposit  their  eggs. 
Many  first  spring  broods  in  temperate  climates  hatch  from  eggs  that 
have  been  carried  over  the  winter  months,  the  eggs  seeming  to  stand 
desiccation  in  dry  locations  to  promptly  hatch  in  pools  left  by  the  spring 


Fig.  11. — Pupa  of  Culex  pungens  at  left;  pupa  of  Anopheles  quad- 
rimaculatus  at  right — greatly  enlarged  (after  Howard,  Bui.  No.  25, 
Bureau  of  Entomology,  Dept.  of  Agr.). 


rains,  or  even  in  water  from  melting  snow  during  the  warmer  days  of 
late  winter. 

In  refutation  of  the  assertion  often  made  that  mosquitoes  cannot 
ovulate  without  a  meal  of  warm  blood,  it  has  been  demonstrated  in 
experiments  upon  some  of  our  common  blood-sucking  species  that  fe- 
males as  well  as  males  can  not  only  be  kept  alive  for  a  long  period  when 
given  access  only  to  plants,  but  will,  under  such  conditions,  repeatedl}^ 
breed. 

Pathologic  Importance. — While  their  preference  for  blood  has  made 
them  of  primary  general  interest  as  pests  in  the  habitations  of  man, 
mosquitoes  are  of  the  greatest  importance  medically,  not  only  as  possible 
direct  transmitters  of  disease,  but  as  specific  bearers  of  infection,  bring- 
ing about  such  diseases  as  malaria,  yellow  fever,  and  possibly  filariasis. 
There  have  been  many  convincing  demonstrations  that  malaria  is 
transmitted  exclusively  by  the  bite  of  mosquitoes,  only,  however,  by 
species  belonging  with  the  anopheles  group,  of  which  Anopheles  quadri- 


MOSQUITOES  AND  GNATS 


Fig.  12. — Culex  pungens:  a,  fomalo,  from  side;  b,  male,  from  above;  c,  front 
tarsus  of  same;  d,  middle  tarsus;  e,  hind  tarsus;  f,  genitalia  of  same,  i,  scales  from 
hind  border  of  wing;  h.  scales  from  disk  of  wing — enlarged  (after  Howard,  Bui. 
No.  4,  Bureau  of  Entomology,  Dept.  of  Agr.). 


28 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


m-aculatus  (Fig.  13)  and  A.  punctipennis  have  been  most  often  observed 
in  the  United  States.  While  elaborate  keys  and  tables  are  necessary  even 
to  the  entomologist  for  more  exact  differentiation,  it  is  not  a  difficult 
matter  to  decide  whether  a  mosquito  is  or  is  not  a  transmitter  of  malaria, 


Fig.  13. — Anopheles  quadrimaculatus:  Adult:  male  at  left,  fe- 
male at  right — enlarged  (after  Howard,  Bui.  No.  25,  Bureau  of 
Entomology,  Dept.  of  Agr.). 

the  two  genera  Ciilex  and  Anopheles  being  readily  distinguished  by  the 
following  more  prominent  characteristics : 

The  adult  Culex,  when  at  rest  upon  a  wall,  usually  holds  the  body 


Fig.  14. — Anopheles  at  left,   Culex   at   right — enlarged    (after  Howard,   Bui.    No.   25, 
Bureau  of  Entomology,  Dept.  of  Agr.). 

parallel  with  the  wall,  or  with  the  abdomen  slightly  inclined  toward  it, 
the  angle  formed  by  the  abdomen  with  the  head  and  thorax  giving  a 


MOSQUITOES  AND  GNATS 


29 


hunchback  appearance.  The  proboscis  projects  forward  but  not  suffi- 
ciently so  as  to  be  on  a  line  with  the  axis  of  the  body  (Fig.  14).  The 
palpi  in  the  female  are  short,  in  the  male  usually  long.  The  wings,  as  a 
lule,  are  without  spots. 

Adults  of  the  anopheles  group  when  thus  at  rest  hold  the  body  at  an 
angle  of  about  forty-five  degrees  with  the  wall's  surface,  the  abdomen 
directed  outward  (Fig. 
14) .  The  proboscis 
projects  forward  on  a 
line  with  the  axis  of 
the  body.  In  both 
sexes  the  palpi  are 
about  as  long  as  the 
proboscis.  The  wings 
are  usually  spotted. 

The  larva  of  Culex, 
when  at  the  surface 
of  the  water,  rests  in 
an  oblique  or  vertical  _ 
position  with  the  re- 
spiratory tube  at  the 
exact  surface  (Fig.  15). 

The  resting  larva  of 
Anopheles  floats  in  a 
horizontal  position  just 
beneath  the  surface. 
There  is  no  respiratory 
tube,  the  spiracles 
opening  on  the  eighth 
abdominal  segment 
which  is  applied  to 
the  surface  (Fig.  15). 

Eggs  of  Culex  are  de- 
posited upon  water  in 
masses,  the  rafts  of  eggs 
often  being  more  or  less 
boat-shaped  (Fig.  10). 

Anopheles  lay  their  eggs  upon  water  unmassed,  the  eggs  floating 
singly  by  lateral  expansions  (Fig.  16). 

The  mosquito  breeding  in  our  Southern  States  which  carries  yellow 
fever  from  man  to  man,  ^Edes  calopus  iStegomija  calopiis,  S.  fasciata), 
is  rather  peculiarly  marked.  Upon  each  side  of  the  thorax  is  a  broad, 
silveiy,  curved  line,  between  which  there  are  two  parallel  median  lines 
and  a  slender  discontinuous  line,  the  whole  pattern  presenting  somewhat 


Fig.  15. — At  top,  half  grown  larva  of  Anopheles  in 
breathing  position,  just  beneath  the  surface  film.  At 
bottom,  half  grown  larva  of  Culex  in  breathing  position 
— greatly  enlarged  (after  Howard,  Bui.  No.  25,  Bureau 
of  Entomology,  Dept.  of  Agr.)- 


30 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


the  shape  of  a  lyre.  At  the  base  of  each  abdominal  segment  is  a  narrow, 
silvery  band,  while  on  each  side  there  is  a  silvery  spot.  At  the  base  of 
each  segment  of  the  black  legs  there  is  a  distinct  white  band. 

Highly  domestic,  this  species  will  breed  in  collections  of  water  about 
and  within  the  habitations  of  man,  the  larvae  often  being  found  in  small 
household  water  receptacles,  such  as  flower  pots,  vases,  etc.  Of  its 
habits  acquired  by  long  association  with  man,  Howard  thus  speaks:  "It 
approaches  stealthily  from  behind,  retreating  upon  the  slightest  alarm. 


Fig.  16. — Group  of  eggs  of  Anopheles  quadrimaculatus  as  they  appear  resting 
naturally  on  the  surface  of  the  water— enlarged  (after  Howard,  Bui.  No.  25, 
Bureau  of  Entomology,  Dept.  of  Agr.). 

The  ankles  and,  when  one  is'sittmg  at  a  table  or  desk,  the  under  side  of 
the  hands  and  wrists  are  favorable  points  of  attack.  It  attacks  silently, 
whereas  other  mosquitoes  have  a  piping  or  humming  note.  The  warning 
sound  has  doubtless  been  suppressed  in  the  evolutionary  process  of  its 
adaptation  to  man.  It  is  extremely  wary.  It  hides  whenever  it  can, 
concealing  itself  in  garments,  working  into  the  pockets  and  under  the 
lapels  of  coats,  and  crawling  up  under  the  clothes  to  bite  the  legs.  In 
houses  it  will  hide  in  dark  corners,  under  picture  moldings  and  behind 
the  heads  of  old-fashioned  bedsteads.  It  will  enter  closets  and  hide  in 
the  folds  of  garments." 


MOSQUITOES  AND  GNATS  31 

Effect  upon  Live  Stock. — That  mosquitoes  are  a  source  of  much 
annoyance  and  actual  suffering  to  live  stock  can  be  attested  to  by  stock- 
men. Horses  and  cattle  pasturing  upon  low  lands  and  amid  vegetation 
where  the  insects  abound  are  especially  exposed  to  attack,  the  pests 
often  hovering  about  them  in  clouds,  while  upon  the  bodies  of  the 
animals  large  numbers  may  be  seen  with  abdomens  engorged  with  the 
blood  of  their  victims.  Loss  of  condition  and  the  falling  off  of  produc- 
tiveness in  dairy  herds  must  essentially  follow  this  interference  with 
their  pasturage  and  comfort. 

Control. — The  most  effectual  preventive  measures  dealing  with  mos- 
quitoes are  those  directed  against  the  larvie.  The  abolition  of  breeding 
places  being  of  first  importance,  all  receptacles  for  standing  water,  such 
as  rain  barrels,  cans,  vaults,  gutters,  etc.,  should  be  removed,  covered,  or 
otherwise  made  impossible  to  access  and  propagation  of  mosquitoes. 
Pools  should  be  drained,  or,  if  this  is  not  feasible,  ma^-  be  treated  with 
kerosene;  or  small  fish,  which  feed  upon  the  larvae,  may  be  introduced 
into  the  mosquito-breeding  ponds.  The  quickest  and  most  satisfactory 
way  to  destroy  larvae  and  pupae  is  by  the  formation  of  the  kerosene 
film  upon  the  water's  surface.  The  oil  is  best  applied  for  this  purpose 
as  a  spray,  or,  if  but  a  small  area  is  to  be  treated,  it  may  be  thrown  upon 
the  surface  and  the  water  then  vigorously  stirred.  About  one  ounce  of 
kerosene  to  fifteen  square  feet  of  water  surface  will  be  sufficient,  and  this 
application  should  be  repeated  at  intervals  of  about  three  weeks. 

Such  measures  are  directed  only  against  local  species,  and,  essentially, 
there  must  be  community  action  for  it  to  be  effective.  Migratory  forms, 
such  as  are  bred  in  the  marshes  near  our  coasts,  cannot  thus  be  reached, 
their  eradication  constituting  a  problem  demanding  state  control. 

For  indoor  protection  in  mosquito-infested  districts,  screening  is  of 
course  essential.  In  spite  of  the  most  thorough  screening,  however, 
mosquitoes  will  enter  in  various  ways,  as  through  openmg  doors  and  upon 
the  clothing  of  persons  passing  in.  As  remedies  against  those  which 
have  gained  access  to  houses  various  kinds  of  repellents  are  used.  Burn- 
ing pyrethrum  powder  will  often  rid  a  room  of  mosquitoes,  a  convenient 
method  being  to  sprinkle  the  powder  upon  a  heated  shovel;  or  small 
cones  may  be  molded  from  the  dampened  powder  and,  after  drying, 
burned.  Oil  of  pennyroyal  or  citronella  applied  to  handkerchiefs  or 
lightly  touched  to  the  hands  and  face,  though  objectionable  to  some, 
will  usually  insure  a  ]5eaceful  night  against  the  pests. 

Family  II.  Simuliid.e 

Dipt  era  (p.  23).  The  flies  of  this  family  are  known  as  black  flies, 
black  gnats,  or  buffalo  gnats,  the  latter  name  derived  from  their  peculiar 
humpback  appearance.    They  are  dark  colored,  with  short  thick  body, 


32 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


short  eleven-segmented  antennae,  no  single  eyes,  broad  wings,  and  stout 
legs.    Only  the  females  are  provided  with  piercing  mouth  parts. 

The  larvae,  so  far  as  known,  are  aquatic.  The  eggs  are  deposited  in  a 
compact  layer  upon  some  object,  usually  rock,  near  the  surface  of  a 
flowiiig  stream.  Upon  hatching  the  larvae  drop  into  the  stream  and  live 
attached  to  sticks,  stones,  or  other  objects  under  the  surface  of  swiftly 
running  water.  They  may  detach  themselves  and  move  about  in  a 
looping  manner  similar  to  that  of  the  measuring  worm,  or  they  may 
be  carried  by  the  current  for  considerable  distances.  Respiration  is 
carried  on  by  gill-like  processes. 

SiMULIUM    PeCUARUM 

The  Southern  Buffalo  Gnat  (Fig.  17).  Simuliidae  (p.  31).  The  adult 
female  is  nearly  a  quarter  of  an  inch  in  length,  the  male  somewhat 

smaller.  The  color  of  the  body  is 
black,  and  it  is  covered  with  light 
brown  hairs  which  are  arranged  upon 
the  thorax  in  such  a  manner  as  to  give 
a  longitudinal  striped  appearance,  the 
abdomen  showing  upon  its  dorsal  side 
a  broad  grayish  stripe  widening  out 
toward  the  abdominal  apex.  The 
male  notably  differs  from  the  female 
in  that  the  eyes  are  much  larger  and 
join  each  other  in  the  middle  line. 
The  individual  facets  on  the'  upper 
part  of  the  eye  are  considerably  larger 
than  those  of  the  female. 

The  larva  (Fig.  18)  agrees  in  gen- 
eral appearance  with  that  of  other 
species  of  Simulium.  It  is  about 
three-eighths  of  an  inch  in  length, 
twelve-segmented,  somewhat  con- 
stricted in  the  middle,  enlarging  to- 
ward both  ends.  The  posterior  end 
is  the  larger  and  is  somewhat  club- 
shaped.  In  addition  to  the  mouth, 
the  head  possesses  two  fan-shaped  bodies  which  are  prehensile  in  func- 
tion. On  the  top  of  the  last  abdominal  segment  there  are  rows  of 
booklets,  while  in  the  vicinity  of  the  rectum  are  organs  of  respiration 
consisting  of  three  tentacles  to  which  the  large  tracheae  lead. 

The  pupa  (Fig.  19)  has  a  peculiar  tuft  of  respiratory  filaments  starting 
from  each  side  of  the  thorax.  The  upper  portion  of  the  pupal  case  is 
open,  exposing  the  head  and  permitting  the  respiratory  filaments  to 


Fig.  17. — Simulium  pecuarum,  female 
— enlarged  (after  Osborn,  Bui.  No.  5, 
Bureau  of  Entomology,  Dept.  of  Agr.). 


MOSQUITOES  AND  GNATS 


33 


have  free  access  to  the  water.     The  pupa  is  firmly  attached  to  sticks, 
leaves,  or  other  submerged  objects.    On  emerging  from  the  pupal  case 
the  fly  at  once  rises  to  the  surface  and,  expanding  its 
wings  as  it  runs  upon  the  water  for  a  short  distance,  flies 
swiftly  away. 

Occurrence  and  Efifect. — The  buft'alo  gnat  has  been 
found  in  Alaska  and  throughout  the  Eastern  United 
States,  but  appears  in  greatest  numbers  in  the  South, 
especially  about  the  mouths  of  rivers  and  creeks.  During 
the  worst  years  the  whole  of  the  Lower  Mississippi  Valley 
as  far  north  as  St.  Louis  may  be  invaded. 

The  attacks  b\'  swarms  of  this  bloodthirsty  and  vic- 
iously active  insect  upon  southern  live  stock  is  a  source 
of  serious  injury  and  loss.  Cattle  and  horses  will  mani- 
fest the  presence  of  the  swarms  by  frantic  efforts  to  de- 
fend against  the  attack,  cattle  rushing  wildly  about  and 
horses  and  mules  trying  to  escape  by  running  awa^-. 
The  most  destructive  raids  of  the  fly  usually  occur  in 
the  months  of  March  and  April.    They  are  exceedingly 

swift  in  their  flight,  darting  at  their     pj^ 
victims  in  search  of  a  suitable  place  to  muiium    pecua- 
draw  blood,  and  in  their  bite  instilling  J"''™' ,^f  Y"^"!"' 

,  T  •        1       1  •      /•  larged  (after  Os- 

a  poison.     Many  ammals  die  irom  ex-  born,  Bui.  No.  5, 
combmed    with    the 


haustion,  combmed  with  the  toxic  Bureau  of  Ento- 
effects  of  the  poison  from  the  bites.  ™°J°^^''  ^^p*-  °^ 
Bronchitis  and  pneumonia,  resultmg 
from  the  inhalation  of  large  numbers  of  the  insects 
from  which  the  exhausted  animal  becomes  totally 
unable  to  defend  itself,  may  also  contribute  to  the 
conditions  leading  to  its  miserable  death. 

Control. — Outbreaks  in  heavily  infested  districts 
may  be  lessened  in  frequence  and  severity  by  the 
clearing  out  of  logs  and  other  debris  in  the  beds  of 
streams,  thus  reducing  the  number  of  objects  for 
attachment  of  the  larvse.  Unlike  those  of  the  mos- 
quito, the  larvae  of  Simulium  thrive  best  in  swiftly 
running  and  well  aerated  water,  therefore  the  re- 
moval of  any  submerged  object  causing  shallow  and  swift h'  moving 
water  reduces  the  possibilities  for  breeding  at  this  point. 

Protection. — The  black  gnat  dislikes  smoke,  therefore,  as  prevention 
against  its  attacks  in  fields  and  barnyards,  the  mamtenance  of  smudges 
is  of  value.  Other  repellents,  such  as  fish  oil,  oil  of  tar,  or  other  oleagin- 
ous and  resinous  substances,  either  singly  or  in  combination,  are 
applied  to  the  surface  of  the  body,  affording  a  measure  of  protection 


Fig.  19. — Simulium 
pecuarum,  pupa — en- 
larged (after  Osborn, 
Bui.  No.  5,  Bureau  of 
Entomologv,  Dept.  of 
Agr.). 


34  PARASITES  OF  THE  DOMESTIC  ANIMALS 

from  attacking  swarms.  The  most  effectual  protective  measure  is  the 
sheltering  of  animals  in  a  cool  dark  stable  during  the  hours  of  the  day 
when  the  swarms  are  most  active. 

Treatment. — Animals  weakened  by  the  bites  may  be  given  a  dif- 
fusive stimulant  and  have  the  parts  locally  treated  with  a  solution  of 
bicarbonate  of  soda  or  ammonia  water. 


CHAPTER  V 
THE  FLIES 

Family  III.  Tabanidae. — Diptera  (p.  23).  This  family  includes 
the  so-called  horseflies  or  gadflies.  The  head  and  e3'es  are  large,  the 
latter  often  of  a  brilliant  color.  The  third  segment  of  the  antennae  has 
four  to  eight  rings.  The  proboscis  of  the  female  is  adapted  for  piercing 
the  skin  of  animals.  The  males  do  not  attack  animals;  their  mouth 
parts  are  less  powerful  than  those  of  the  females  and  are  adapted  for 
feeding  upon  the  juices  of  plants.  The  bod}-  has  fine  hairs;  there  are  no 
bristles.  The  flight  is  strong  and  swift  and  is  accompanied  with  a 
tormenting  buzzing  noise. 

The  eggs  of  Tabanidae  are  deposited  in  masses  upon  vegetation  grow- 
ing in  wet  marshy  ground.  The  larvae  are  carnivorous  and  are  aquatic 
or  live  in  moist  earth. 

Tabaxus  Atratus 

Tabanidae  (p.  35).  This  is  the  common  large  black  horsefly,  having 
a  M'ide  distribution  in  the  United  States.  It  is  one  of  the  larger  species 
of  the  family,  measuring  an  inch  or  more  m  length  and  having  a  body  so 
uniformilv  black  as  to  attract  attention  even  when  it  is  upon  the  wing 
(Fig.  20)." 

The  eggs  are  deposited  in  masses,  usually  upon  the  stems  of  plants  or 
grasses  growing  in  the  vicinity  of  water.  In  about  seven  to  ten  days 
there  is  hatched  a  large  cylindrical  larva  which  tapers  to  a  point  at  both, 
ends  and  has  an  integiunent  that  is  somewhat  transparent  (Fig.  20,  a). 
At  this  stage  it  lives  mostl}^  in  moist  earth  into  which  it  burrows  actively, 
feeding  mainly  upon  worms  and  the  larvae  of  other  insects.  While  the 
period  of  larval  life  is  long,  in  some  observed  cases  lasting  several  months 
to  a  year,  the  stage  of  the  pupa  (Fig.  20,  b)  is  short,  the  fly  emerging  from 
its  case  after  a  few  daj-s  of  pupation.  It  is  probable  that  the  broods  are 
carried  over  the  winter  in  the  larval  stage. 

Effect. — The  black  horsefly  is  common  throughout  the  summer 
months,  attacking  cattle  and  horses  usualh'  in  the  open  sunny  pasture, 
and  inflicting  with  its  long  piercing  mouth  parts  a  painful  wound.  For- 
tunately it  does  not  attack  in  swarms  as  does  the  buffalo  gnat,  nor  does 
it  instill  with  its  bite  as  much  poison.  There  is  evidence  of  the  severity 
of  its  wound,  however,  in  the  drop  of  blood  which  wells  up  from  the  seat 
of  puncture  after  the  insect  has  left  its  victim.     While  there  is  little 


36  PARASITES  OF  THE  DOMESTIC  ANIIVIALS 

after-effect  from  the  bites  of  these  flies  they  are  a  source  of  much  tor- 
ment to  Hve  stock,  not  only  in  the  pain  produced  by  their  punctures, 
but  in  their  pecuhar  buzzing,  which  often  terrorizes  nervous  animals, 

their  frantic  and  heed- 
less efforts  to  escape  not 
infrequentlj^  resulting 
in  injury. 

There  can  be  no 
doubt  that  the  Taba- 
nidae  are  concerned  in 
the  transmission  of  cer- 
tain blood  diseases  of 
live  stock.  It  is  signif- 
icant as  to  their  possi- 
bihties  as  carriers  of 
anthrax  that  their  at- 
tack seems  to  be  more 
commonl}'-  d  ir  e  c  t  e  d 
against  cattle  than 
horses. 

Protection.  —  Little 
can  be  done  toward 
repelling  the  attacks  of  the  flies.  Horses  at  work  are  protected  in  a 
measure  by  covering  them  with  nets.  Where  the  flies  are  numerous  and 
especially  tormenting  it  is  advisable  to  remove  pasturing  animals  to  a 
well-shaded  retreat  during  the  warmer  and  sunnier  parts  of  the  day. 


Fig.  20. — Tabanus  atratus:  a,  larva;  b,  pupa;  c,  adult 
(after  Osborn,  from  Riley,  Bui.  No.  5,  Bureau  of  Ento- 
mology, Dept.  of  Agr.). 


Tabanus  Lineola 

Tabanidffi  (p.  35).— The  Green-head  Horsefly  (Fig.  21).  This  is  the 
most  widely  distributed  species  in  North  America.  It  is  about  five- 
eighths  of  an  inch  in  length.  E^^es  large  and  bril- 
liant green,  abdomen  brown,  with  a  conspicuous 
grayish  line  running  longitudinally  on  its  dorsal 
side.  It  is  from  this  marking  that  its  specific 
name  is  derived,  while  the  peculiar  coloring  of  the 
eyes  gives  to  it  the  common  name  "Green-head." 

The  oval,  larval,  and  pupal  stages  are  passed  uneok    (after    Osbom; 
in  moist  places,  and  in  other  respects  the  life  cycle  from  Packard,  Bui.  No.  5, 
is  similar  to  that  of  Tabanus  atratus,  though  the 
larval  period  is  probably  not  so  long. 

The  Green-heads  appear  in  especially  large  numbers  in  marsh}^  dis- 
tricts during  the  brightest  and  hottest  days  of  the  summer.  They 
attack  in  greater  numbers  than  the  Black  Horseflies,  and,  especially 


Fig.    21.  —  Tabanus 


Bureau   of   Entomology, 
Dept.  of  Agr.). 


.  THE  FLIES  37 

during  warm  and  sunny  weather,  their  harassing  bites  cause  much 
torture  to  horses  and  cattle.  They  do  not  fly  in  cloudy  weather,  and 
they  perish  with  the  frosts  of  earl}^  autumn. 

Family  IV.     Muscid.e 

Diptera  (p.  23). — These  flies  are  small  to  moderately  large,  with  bodies 
thinly  covered  with  hairs  or  bare.  The  bristles  of  antennae  are  feathery. 
The  abdomen  is  four-segmented  and  smooth  except  for  bristles  near  the 

The  larvae  are  apodal  maggots,  feeding  upon  decaying  animal  or  veg- 
etable matter. 

MUSCA   DOMESTICA 

The  common  house  fly  (Fig.  8).  Muscidae  (p.  37). — The  mature  in- 
sect is  02ie-fourth  to  five-sixteenths  of  an  inch  in  length;  dorsal  region  of 
thorax  grayish  in  color  and  bearing  four  longitudinal  stripes;  abdomen 
yellowish.  The  mouth  parts  are  trumpet-shaped,  adapted  for  sucking 
up  liquids  but  not  for  piercing. 

Life  History. — In  about  ten  days  after  emerging  from  the  pupal 
case  the  female  fly  seeks  suitable  material  upon  which  to  deposit  her 
eggs.  This  may  be  any  decaying  vegetable  matter,  though  usually 
horse  stable  manure.  About  one  hundred  eggs  are  deposited  at  each 
laying,  of  which  there  are  several  at  intervals  of  three  to  five  days.  In 
eight  to  twentj^-four  hours  a  white,  footless  larva  is  hatched.  After 
five  daJ^s  to  one  week  of  feeding  and  and  growing,  during  which  period 
it  undergoes  two  molts,  the  larva  enters  the  pupal  stage,  the  larval  skin 
serving  as  its  puparium.  Before  entei'ing  this  stage  the  maggot  may 
crawl  away  from  its  breeding  place  and  burrow  for  a  short  distance 
into  the  adjacent  ground,  or  find  lodgment  under  a  board,  stone,  or 
dried  crust  of  manure.  The  stage  of  pupation  lasts  from  five  days  to 
one  week,  and  at  its  termination  the  adult  fly  emerges. 

According  to  the  longer  periods  given,  the  time  required  for  develop- 
ment from  the  egg  to  the  imago  is  fifteen  days.  This  time,  however,  is 
greatly  influenced  by  temperature,  under  the  most  favorable  conditions 
of  which  the  period  for  complete  metamorphosis  may  be  reduced  to  ten 
days;  a  fact  always  to  be  reckoned  with  in  dealing  with  control  of  the  fly 
through  the  regiilar  and  systematic  removal  of  stable  manure  or  other 
material  which  may  serve  as  its  breeding  bed. 

In  the  warm  midsummer  season  adult  flies  may  live  for  six  to  eight 
weeks,  though  it  is  probable  that  the  average  period  will  not  exceed 
thirty  days.  The}'  may  survive  the  winter  in  a  state  of  hibernation, 
seeking  their  retreats  in  the  late  fall  months,  and  coming  forth  with  the 
warm  da^'s  of  early  spring  to  crawl  upon  the  windows  as  they  seek  the 
warm  sunlight  or  exit  from  houses. 


38  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Habits  and  Relation  to  Disease.— While,  so  far  as  known,  the 
house  fly  is  not  an  essential  host  to  pathogenic  organisms  of  man  and 
the  mammalian  domesticated  animals,  it  is,  by  its  structure  and  filthy 
habits  of  feeding,  one  of  the  most  dangerous  of  disease-transmitting 
insects.  Omniverous  in  habit,  it  will  feed  upon  decaying  vegetable  and 
putrid  animal  matter,  excrement,  vomit,  sputum,  or  other  revoltingly 
filthy  material.  Direct  from  such  sources  of  infection  it  may  pass  to 
the  food  upon  our  tables  to  which  it  is  equally  attracted,  leaving  a 
trail  of  contamination  wherever  it  may  drag  its  filthy  parts. 

From  the  viewpoint  of  the  bacteriologist  it  would  seem  superfluous  to 
discuss  the  house  fly  as  a  carrier  of  disease-producing  bacteria.  The 
form  of  its  proboscis,  habit  of  regurgitating  its  food,  its  six  bristly  feet 
(Fig.  8),  each  terminated  by  a  sponge-like  structure  secreting  a  stick}'- 
substance,  together  with  the  vile  material  which  it  visits,  make  it  both 
by  structure  and  habit  an  ideal  transmitter  of  such  infectious  diseases  as 
typhoid  fever,  dysentery,  cholera,  glanders,  anthrax,  and  ophthalmia. 
Furthermore,  positive  evidence  of  the  degree  to  which  this  insect  is  a 
carrier  of  bacteria  has  been  well  set  forth  by  laborator}^  experiment. 

Control. — As  a  widely  disseminated  menace  to  public  health  the 
house  fly  presents  a  problem  that  can  only  be  successfully  dealt  with  by 
community  action.  The  measures  taken  should  look  to  control  rather 
than  elimination,  the  latter,  however  desirable,  being  scarcely  possible 
under  present  conditions.  While  it  prefers  horse  manure,  it  is  known 
that  almost  any  fermenting  material  will  serve  as  a  breeding  place,  and 
it  therefore  follows  that,  in  order  to  successfully  combat  this  pest  through 
its  sources  of  propagation,  all  such  material  must  be  systematically  re- 
moved, screened  off,  or  so  treated  as  to  render  it  unsuitable  for  the 
development  of  the  larvae.  Manure  should  be  removed  at  least  once  a 
week,  and  if  possible  at  once  spread  upon  the  fields.  Kitchen  garbage 
should  be  likewise  removed,  and  in  the  meantime  kept  in  tightly  closed 
receptacles.  Access  of  flies  to  the  vaults  of  outhouses  can  be  prevented 
by  their  proper  structure  and  screening. 

Protection. — As  to  measures  of  protection  to  the  household  against 
flies,  there  is  little  to  be  said  that  is  not  of  common  knowledge.  The 
first  of  these  to  be  mentioned  is  the  thorough  screening  of  doors  and 
windows.  Kitchens  being  especially  attractive  to  flies,  they  should  be 
doubly  protected  by  screening  the  back  porch,  the  screen  doors  at  these 
locations  being  well  fitting  and  made  to  withstand  their  frequent  use. 
Flies  that  have  gained  entrance  are  best  gotten  rid  of  by  burning  pyre- 
thrum  powder.  A  good  method  for  the  treatment  of  a  room  is  to  sprinkle 
the  powder  upon  a  hot  shovel  after  first  closing  the  doors  and  windows; 
if  the  kitchen,  the  powder  may  be  sprinkled  over  the  stove.  It  is  best 
applied  at  night,  leaving  the  room  tightly  closed.  In  the  morning  the 
flies  will  be  found  lying  about  dead  or  stupefied,  when  they  may  be 


THE  FLIES  39 

swept  up  and  Ijurnod.  The  use  of  poisonous  liquids  set  around  in  dishes 
has  but  httle  efficacy  and  for  other  reasons  is  not  to  be  reconunended. 
Sticky  .fly  paper,  to  be  most  effectual,  should  be  placed  in  parts  of  the 
room  where  there  is  most  sunlight,  as  in  the  vicinity  of  windows. 

In  this  connection  it  should  be  borne  in  mind  that  adult  house  flies 
and  their  allies  seek  the  light,  while  their  larvse  avoid  it,  characteristics 
referred  to  in  the  first  case  as  light  positive  and  in  the  second  as  light 
negative.  This  habit  as  to  light  is  to  be  reckoned  with  and  taken  ad- 
vantage of  in  measures  looking  to  fly  control. 

Stomoxys  Calcitrans 

Strotnoxys  stabulans.     Sta])le  fly;  stinging  fly.      Muscidse   (p.   37). 
About  the  size  of  the  house  fly.    The  ciplor  is  brownish  gray;  proboscis 
black,  slender,  bent  near  its  base,  and  extending  forward  from  the  head, 
fitted  for  piercing.     The  thorax  bears  four  longi- 
tudinal stripes  which  may  be  more  or  less  broken. 
The  abdomen  is  stout,  grayish,  and  spotted  dor- 
sally.    The  wings  hyaline,  and  when  at  rest  widely 
spread  apart  at  the  tips.     The  fly  rests  with  its 
head  well  elevated  and- with  wings  sloping  later- 
ally downward  and  outward  (Fig.  22). 

The  eggs  are  about  one  nun.  in  length,  cur^'ed 

.,  ,  -i.        •  1        r     •    1  J.  ,         Pig.   22. — btomoxys  cal- 

on  one  side,  on  the  opposite  side  straight  and  eitrans,  enlarged. 
grooved.    The  larva  resemble  those  of  the  house 

fly.  They  ma>'  be  differentiated  by  the  posterior  stigmal  plates, 
which  in  the  larviP  of  the  house  fly  are  large,  irregularly  oval,  and  close 
together,  while  in  Stomoxys  they  are  smaller,  round  or  triangular,  and 
much  farther  apart. 

Life  History. — The  life-cycle  of  the  stable  fly  is  considerably  longer 
than  that  of  the  house  fly;  like  the  latter  it  breeds  in  horse  manure,  but 
not  to  the  same  extent.  Manure  well  mixed  with  straw  is  that  most 
sought.  Ideal  for  the  deposition  of  its  eggs  are  damp  and  fermenting 
collections  of  such  material  as  cut  grass,  alfalfa,  hay,  grain,  or  piles  of 
weeds.  The  eggs  are  deposited  deep  into  the  fermenting  mass,  and, 
under  favorable  conditions  of  temperature,  will  incubate  in  about  three 
days.  The  larvae  are  active  feeders  and  complete  their  growth  in  from 
twelve  to  thirty  days.  As  in  related  flies,  the  puioarium  is  formed  by 
the  hardenhig  of  the  last  larval  skin.  The  duration  of  the  pupal  stage 
will  again  vaiy  according  to  weather,  lasting  from  six  to  twenty  days,  or, 
if  cool,  it  may  be  much  longer.  About  twelve  days  may  be  taken  as  an 
average  period.  The  time  required  for  complete  development  may 
accordingly  be  set  down  as  from  twenty-five  to  thirty  days  under 
ordinarih'  favorable  conditions.  It  is  proi)able  that  the  species  is  car- 
ried over  the  whiter  months  in  our  Northern  States  in  the  larval  and 


40  PARASITES  OF  THE  DOMESTIC  ANIMALS 

pupal  stages.  Development  with  the  appearance  of  adult  flies  will 
occur  in  warm  stables  during  this  season. 

Occurrence  and  Effect. — The  stable  fly  is  of  world-wide  distribution, 
and  is  connnonly  mistaken  for  the  house  fly,  the  term  "biting  house 
fly"  being  often  applied  to  it  from  its  habit  of  entermg  our  houses  durmg 
damp,  rainj^  Vv^eather  and  in  the  cooler  days  of  early  autumn.  It  may 
quickly  be  distinguished  from  the  common  house  fly,  however,  bj^  its 
elevated  head  when  at  rest,  its  protruding,  baj'onet-like  proboscis,  and 
its  wings,  which  are  widely  spread  apart  at  the  tips. 

Though  commonly  called  the  stable  fly,  Stomoxys  is  found  in  far  less 
numbers  about  stables  than  is  the  house  fly,  and,  as  it  will  not  visit  such 
filth  as  does  the  latter,  it  is  not  such  an  offender  agamst  the  cleanliness 
of  dairy  and  other  food  products.  Both  sexes  of  Stomox^'s,  however, 
are  vicious  blood-suckers,  and  their  bite  is  especially  a  source  of  torture 
to  thin-skhmed,  sensitive  animals.  Typically  an  out-of-door  fly,  it  is 
most  likely  to  enter  stables  in  the  cooler  days  of  late  summer  or  early 
autumn  when  it  will  attack  horses  and  cattle,  attaching  itself  by  prefer- 
ence upon  the  legs.  Their  sharp  sting  is  manifested  by  the  stamping, 
kicking,  and  general  restlessness  of  the  victims.  The  punctures  are 
often  followed  by  the  formation  of  papules  which  may  coalesce  and 
rupture,  leaving  a  scaly,  more  or  less  thickened  skin  with  hairs  scant, 
lusterless,  and  erect.  To  the  dairy  they  are  a  source  of  loss  in  milk 
production  through  the  worry  and  unrest  caused  by  their  attacks. 

Relation  to  Disease. — The  possibilities  of  the  stomoxys  fly  as  a 
disseminator  of  infectious  diseases  have  in  recent  years  received  con- 
siderable attention.  Its  habit  of  visiting  a  number  of  hosts  before 
becoming  engorged  with  blood,  together  with  its  deep  puncture,  war- 
rants us  in  charging  agamst  this  species  possibilities  in  the  transmission 
of  anthrax  in  cattle  and  glanders  in  horses.  By  some  authors  it  is  re- 
garded as  a  carrier  of  the  trypanosome  {Trypanosoma  evansi)  which 
produces  surra  of  horses.  Of  this,  however,  there  is  no  conclusive  experi- 
mental evidence.  As  to  the  responsibility  of  the  stable  fly  for  the  spread 
of  infantile  paralysis,  it  will  be  suflficient  here  to  quote  Riley  and  Johann- 
sen,  who,  after  reviewing  the  evidence,  thus  state  their  conclusions 
(1915):  "The  evidence  at  hand  to  date  indicates  that  acute  anterior 
pohomyelitis,  or  infantile  paralysis,  is  transmitted  by  contact  with 
infected  persons.  Under  certain  conditions  insects  may  be  agents  in 
spreading  the  disease,  but  their  role  is  a  subordinate  one." 

Control. — Control  measures  consist  in  removing  materials  which 
afford  favorable  breeding  places  for  the  fly.  Collections  of  moist  and 
fermenting  feed  material,  such  as  have  been  mentioned,  should  be  re- 
moved and  scattered  in  a  layer  suflficiently  thin  to  insure  thorough 
drying.  It  will  then  be  unsuitable  for  the  development  of  stomoxys 
larvae,  as  they  require  considerable  moisture.    Manure  in  which  there  is 


THE  FLIES  41 

mixed  considerable  straw  affords  a  favorable  niediuni  for  the  propaga- 
tion of  this  fl}^ — a  further  reason  for  its  systematic  removal  to  be  at  once 
spread  upon  the  fields,  as  stated  in  control  measures  for  the  house  fly. 
It  should  be  borne  in  mind,  however,  that  stables  are  not  predominant  as 
breeding  places  of  the  fly  under  consideration,  as  is  the  case  with  the 
house  fly.  Stomoxys  is  attracted  to  stables  because  the  animals  from 
which  it  obtains  its  meal  of  blood  are  contained  there.  The  favorite 
material  for  the  deposition  of  its  eggs  is  likely  to  be  found  elsewhere. 
These  flies  like  the  open,  and  chstricts  far  from  stables  may  be  overridden 
with  them. 

Protection. — Little  can  be  done  in  the  way  of  direct  protection  of 
live  stock  against  the  attacks  of  stable  flies  beyond  thorough  screening, 
the  effectiveness  of  which  is  much  lessened  by  the  frequent  opening  of 
doors  customary  about  stables.  Means  of  keeping  them  out  should  be 
especially  looked  to  in  cloudy,  damp  weather,  and  in  the  cool  mornings 
of  early  autumn,  at  which  times  they  are  most  likely  to  seek  the  interior 
of  stables  and  houses. 

Lyperosta  Irritaxs 

Hcematohia  serrata.— The  horn  fly  (Fig.  23).  Muscids  (p.  37).  About 
half  as  large  as  the  house  fly  and  like  it  in  shape  and  color.  The  mouth 
parts  are  adapted  for  piercmg  and  sucking  blood,  but  differ  from  those 
of  the  stable  fly  in  that  the  palpi  are  almost  as  long  as  the  proboscis  and 
are  slightl}'  spatulate. 

The  eggs  (Fig.  23,  a)  are  about  L25  mm.  in  length,  irregularly  oval,  and 
reddish  brown  in  color.  They  are  deposited  in  the  fresh  dung  of  cattle, 
and,  under  favorable  conditions  of  temperature,  will  hatch  in  about 
twenty-four  hours. 

Life  History. — Newly  hatched  larvae  are  about  2.5  mm.  in  length, 
and  pure  white.  When  full  grown  they  are  about  7  mm.  in  length  and 
somewhat  darker  in  color.  The  larvae  burrow  into  the  dung  and  reach 
their  full  growth  in  about  four  days  (Fig.  23,  b).  When  ready  to  trans- 
form into  the  pupal  stage  the  larvse  descend  into  the  dryer  parts  of  the 
dung,  or  for  a  short  distance  into  the  ground  beneath  it.  The  puparium 
(Fig.  23,  c)  is  about  4.5  mm.  in  length,  irregularly  ellipsoidal,  and  dark 
brown  in  color.  The  pupal  stage  occupies  from  five  to  ten  days,  therefore 
the  time  for  full  development  from  the  deposition  of  the  eggs  will  be, 
according  to  the  above,  from  ten  to  fifteen  days. 

Occurrence  and  Habits. — The  horn  fly  is  an  importation  from 
Europe,  making  its  first  appearance  in  the  vicinity  of  Philadelphia  about 
the  year  1886.  It  was  first  noticed  as  a  pest  to  cattle  in  this  country  in 
1887,  from  which  tune  it  has  spread  rapidly  and  at  present  is  found  in 
practically  all  parts  of  the  United  States  and  the  greater  part  of  Canada. 

The  popular  name  ''horn  fly"  is  derived  from  the  habit  peculiar  to 


42 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


this  species  of  clustering  about  the  base  of  the  horn,  though  this  only 
occurs  when  they  are  quite  abundant.  Their  purpose  in  collecting  here 
seems  to  be  for  rest  in  a  location  where  they  are  not  liable  to  be  dis- 
turbed. There  is  a  somewhat  prevalent  belief  that  the  flies  damage  the 
horn  by  eating  into  it,  depositing  eggs,  and  developing  maggots  which 
may  penetrate  to  deeper  structures,  etc.  This  is  a  popular  error  for 
which  there  is  no  foundation,  for,  beyond  "fly  specking,"  it  has  not  been 
observed  that  the  flies  do  any  injury  to  the  horn. 

Field  study  will  show  that  this  insect  assumes  two  characteristic  posi- 
tions.   In  the  resting  position,  as  they  are  found  when  upon  the  horns. 


Fig.  23. — Lyperosia  irritans:  a,  egg;  b,  larva;  c,  puparium;  d,  adult  in  biting 
position — all  enlarged  (after  Osborn,  from  Riley  and  Howard,  Bui.  No.  5,  Bu- 
reau of  Entomology,  Dept.  of  Agr.). 

the  wings  are  held  nearly  flat  down  the  back,  overlapping  at  their  bases 
and  moderately  diverging  at  their  tips.  The  proboscis  is  extended  for- 
ward, and  the  legs  are  not  widely  spread.  When  active  and  feeding,  on 
the  other  hand,  the  wdngs  are  slightly  elevated  and  held  almost  at  right 
angles  to  the  body,  while  the  legs  are  spread.  The  proboscis  is  nearly 
perpendicular  in  position,  and  penetrates  the  skin  of  the  animal  at- 
tacked. To  secure  this  position  it  works  its  way  to  the  skin,  and  is 
usually  observed  more  or  less  covered  by  the  hairs.  In  damp,  rainy 
weather  they  may  be  noticed  as  particularly  abundant  beneath  the 
hairs  of  the  ventral  surface  of  the  body. 

Effect. — Horn  flies  appear  early  in  May  and  become  most  abundant 
in  July  and  August.    With  the  coming  of  cold  weather  they  disappear, 


THE  FLIES  43 

their  full  period  depending  uiDon  season  and  latitude.  During  the  time 
of  their  activity  they  are  a  veritable  pest  to  cattle,  causing  interference 
with  their  grazing  and  disturbance  of  their  rest,  with  consequent  un- 
thrift  and  serious  loss  in  productiveness.  Horses  do  not  escape  their 
annoyance,  but  cattle  seem  to  be  the  special  object  of  their  attack. 
Though  the  damage  done  is  chiefly  through  their  torment,  the  con- 
siderable amount  of  blood  extracted  from  the  animal  by  the  large 
swarms  which  feed  upon  it  must  seriously  contribute  to  the  weakening 
effects.  Further,  as  in  all  blood-sucking  Diptera  visiting  cattle,  we  are 
justified  in  inferring  that  this  fly  may  be  a  transmitter  of  infectious  blood 
diseases,  such  as  anthrax,  though  as  to  this  there  has  as  yet  been  little 
if  any  investigation. 

Control. — In  control  measures  two  lines  of  procedure  should  be  fol- 
lowed, one  looking  to  prevention  of  multiplication,  the  other  directly 
protecting  cattle  from  attack.  Of  these  the  former  is  most  effective  and 
involves,  such  treatment  of  breeding  places  as  will  prevent  larval  develop- 
ment. As  eggs  are  deposited  in  fresh  dung,  which  must  remain  moist  for 
the  proper  nourishment  of  the  hatched  larvae,  any  treatment  of  the 
droppings  which  will  cause  them  to  rapidly  dry  out  will  prevent  or 
greatly  inhibit  larval  development.  Scattering  or  thinly  spreading  this 
manure,  as  may  be  done  by  a  rake  or  by  drawing  })rush  across  the  fields, 
will  accomplish  this;  the  latter  method,  more  economical  in  time  and 
labor,  is  best  adapted  for  large  pasture  areas.  Hogs  running  with  cattle 
will  serve  to  scatter  the  manure  to  a  large  extent.  The  use  of  lime,  which 
may  be  applied  by  simply  throwing  it  over  the  droppings  in  the  pasture, 
is  very  effective  in  destroying  the  larvae.  While  piles  of  cow  manure, 
especially  those  containing  considerable  straw,  afford  good  breeding 
places  for  the  stable  fly,  the  horn  fly  will  not  seek  this  material  to  any 
great  extent  for  the  deposition  of  its  eggs. 

Protection. — For  the  direct  protection  of  cattle  a  number  of  oleagin- 
nous  repellents  are  recommended.  A  mixture  of  fish  oil  and  tar,  equal 
parts,  applied  to  the  regions  most  attacked,  is  one  in  general  use.  Almost 
any  oily  or  greasy  substance  is  of  value,  though  causing  the  animal  to 
become  somewhat  unsightly  from  adhermg  collections  of  dust  and  dirt. 
Sprays  of  kerosene  emulsion  (page  48)  may  be  used  with  advantage, 
though  the  effectiveness  of  such  treatment  is  very  transient.  The 
following  mixture  is  recommended  by  the  Kansas  Experiment  Station: 
resin  (pulverized),  one  part;  shaved  soap,  one  part;  water,  one-half  part; 
fish  oil,  one  part;  oil  of  tar,  one  part;  kerosene,  one  part;  water,  three 
parts.  The  resin,  soap,  fish  oil,  and  one-half  part  water  are  boiled  to- 
gether until  the  resin  is  dissolved,  then  the  three  parts  water  are  added, 
and  finally  the  kerosene  and  oil  of  tar.  The  mixture  should  be  thor- 
oughly stirred  and  lioiled  for  fifteen  minutes.  This  preparation  when 
cool  and  applied  as  a  spray  will  act  as  an  effective  repellent  for  twenty- 


44 


PARASITES  OF  THE  DOMESTIC  ANIIVIALS 


four  to  forty-eight  hours.  It  is  necessar}-,  therefore,  to  regularly  repeat 
the  application  if  the  animals  are  to  be  continuously  protected.  Re- 
pelling agents  are  best  applied  in  the  evenmg  when  cattle  are  stabled  or 
yarded. 

Tsetse  Flies 

Genus  Glossina.— Muscidge  (p.  37).  The  tsetse  flies  (Fig.  24)  are 
about  the  size  of  house  flies,  or  may  be  somewhat  larger.  The  general 
color  is  light  brown.  When  at  rest  the  proboscis  projects  in  front  of  the 
head.     At  the  base  of  the  proboscis  is  a  bulbous  enlargement,    arista 


Fig.  24.— Tsetse  fly. 

plumose  above.    The  resting  wings  are  folded  scissors-like  over  the  back. 

These  flies  are  found  only  in  certain  areas  in  Africa. 

Glossina  Palpalis.— Glossina  (p.  44).  This  species  is  8  to  9  mm. 
(5/16  to  3/8  of  an  inch)  in  length.  The  color  is  brown  dusted  with  gray. 
The  antennae  are  black.  All  segments  in  the  hind  tarsi  are  black.  The 
fourth  and  fifth  segments  of  the  fore  tarsi  are  black.  The  halteres  are 
white. 

Glossina  Morsitans.— Glossina  (p.  44).  About  the  same  size  and 
color  as  G.  palpalis.  The  antennae  are  dark.  The  first  three  segments 
of  the  hind  tarsi  are  yellow,  the  fourth  and  fifth  segments  black.  The 
fourth  and  fifth  segments  of  the  first  and  second  pairs  of  tarsi  are  black. 
^  Glossina  longipalpis  is  a  species  which  in  characteristics  and  distribu- 
tion is  almost  identical  with  G.  morsitans. 

Breeding  Habits  and  Habitat.— The  Glossina  deposit  hatched  larva 
among  roots  of  tropical  vegetation.    When  deposited  the  larvae  are  well 


THE  FLIES  45 

advanced  and  within  a  few  hours  enter  upon  the  pupal  stage  which  re- 
quires from  six  to  eight  weeks.  Occurring  only  in  Africa,  they  are  most 
abundant  in  heavily  wooded  districts  penetrated  by  water  courses. 
Both  sexes  are  blood-sucking,  and  it  is  in  such  locations  that  they  are 
most  likely  to  find  the  wild  animals  upon  which  they  feed. 

Relationship  to  Trypanosomiasis. — As  transmitters  of  trypanoso- 
miasis to  man  and  domestic  aniinals,  tsetse  flies  maj'  be  regarded  as  the 
world's  most  dangerous  insects.  The  first  observation  of  trj'panosomes 
in  the  blood  of  mammals  was  made  b}^  Lewis,  who  in  1877  described  a 
trypanosome  {Trypanosoma  lewisi)  of  the  blood  of  a  rat.  Three  years 
later  another  trj^panosome  (7".  evansi)  was  studied  as  the  cause  of  surra 
in  horses.  When  Bruce  in  1894  demonstrated  the  relationship  between 
tsetse  fly  disease  of  horses  in  Africa,  the  cause  of  which  was  unknown, 
and  nagana,  trypanosomes  received  much  more  attention  as  to  their 
pathogenic  importance.  The  further  investigations  of  Bruce  as  to  the 
part  played  by  the  tsetse  fly  in  the  transmission  of  this  disease  are  best 
given  in  his  own  account,  from  which  the  following  is  an  excerpt: 

"When  it  was  once  established  that  the  two  diseases  were  the  same, 
experiments  were  made  to  And  out  how  the  animals  became  infected, 
whether  the  fly  was  the  carrier  or  the  mere  concomitant  of  the  low-lying, 
mihealthy  district,  and,  if  a  carrier,  if  it  was  the  only  carrier  of  the  disease 
from  sick  to  healthy  animals.  Horses  taken  down  into  the  fly  country, 
and  not  allowed  to  feed  or  drink  there,  took  the  disease.  Bundles  of 
grass  and  supplies  of  water,  brought  from  the  most  deadly  parts  of  the 
fly  country  to  the  top  of  Ubombo  and  there  used  for  fodder  for  healthy 
horses  failed  to  convey  the  disease.  Tsetse  flies  caught  in  the  low  country 
and  kept  in  cages  on  top  of  the  mountain,  when  fed  on  affected  animals, 
were  capable  of  giving  rise  to  the  disease  in  healthy  animals  up  to  forty- 
eight  hours  after  feeding.  Tsetse  flies  brought  up  from  the  low  country 
and  placed  straight  way  upon  healthy  animals  were  also  found  to  give 
rise  to  the  disease.  The  flies  were  never  found  to  retam  the  power  of 
infection  for  more  than  forty-eight  hours  after  they  had  fed  upon  a  sick 
animal,  so  that  if  wild  tsetse  flies  were  brought  up  from  the  low  country, 
kept  without  food  for  three  days,  and  then  fed  on  a  healthy  dog,  they 
never  gave  rise  to  the  disease.  In  this  way  it  was  proved  that  the  tsetse 
fly,  and  it  alone,  was  the  carrier  of  nagana.  Then  the  question  arose  as 
to  where  the  tsetse  flies  obtained  the  trypanosomes.  The  flies  lived 
among  the  wild  animals,  such  as  buffaloes,  koodoos,  and  other  species  of 
antelopes,  and  naturally  fed  on  them.  It  seemed  that,  in  all  probabilitj^, 
the  reservoir  of  the  disease  was  to  be  found  in  the  wild  animals.  There- 
fore, all  the  different  species  of  wild  animals  obtainable  were  examined 
both  by  the  injection  of  their  blood  into  healthy  susceptible  animals, 
and  also  by  direct  microscopic  examination  of  the  blood  itself.  In  this 
way  it  was  discovered  that  manv  of  the  wild  animals  harbored  this 


46  PARASITES  OF  THE  DOMESTIC  ANIMALS 

trypanosome  in  their  blood.  The  parasites  were  never  numerous,  so 
that  it  was  only  after  a  long  search  that  they  could  be  discovered  by  the 
microscope  alone.  The  wild  animals  did  not  seem  to  be  affected  by  the 
trypanosomes  in  any  way;  they  showed  no  signs  or  sjanptoms  of  the 
disease,  and  it,  therefore,  appeared  probable  that  the  tiypanosomes  lived 
in  their  blood  as  harmless  guests,  just  as  the  trypanosome  of  the  rat  lives 
in  the  blood  of  that  animal." 

As  Trypanosomu  brucei  is  now  known  to  be  the  organism  causing  the 
fatal  nagana  of  horses  and  mules  of  Africa,  so  T.  gamhiense  is  known  to 
be  the  cause  of  sleeping  sickness  of  man.  The  relationship  of  the  tsetse 
fly  to  human  trypanosomiasis  was  shown  in  a  way  very  similar  to  that 
by  which  Bruce  reached  his  conclusions.  While  the  tsetse  species 
Glossina  morsitans  and  G.  longipalpis  are  especially  concerned  in  the 
transmission  of  nagana,  and  G.  palpalis  likewise  related  to  sleeping  sick- 
ness, it  has  been  shown  by  students  in  the  field  of  protozoology  that  not 
only  biting  flies,  but  mosquitoes,  lice,  and  leeches  may  carry  trypano- 
somes from  one  vertebrate  host  to  another. 

Experiment  has  shown  that  the  trypanosomes  adhering  to  the  pro- 
boscis of  the  biting  fly  after  it  has  fed  upon  the  blood  of  an  infected 
animal  rapidly  lose  their  vitality,  becoming  sufficiently  attenuated 
within  fortj'-eight  hours  to  be  noninfective.  The  fl}',  therefore,  can 
only  inoculate  mechanicalh^  that  is  by  the  puncture  of  its  soiled  pro- 
boscis," within  a  few  hours  after  it  has  become  a  carrier  of  the  infecting 
organism.  It  is  now  known,  however,  that  trypanosomes  taken  into 
the  stomach  of  the  fly  with  its  meal  of  blood  pass  through  a  metamor- 
phosis involving  sexual  forms,  and  that  at  the  end  of  about  twentj'-eight 
days  the  fly  may  again  become  infective.  At  this  time  the  parasites 
have  reached  the  salivary  glands  and  here  they  remain  during  the  re- 
mainder of  the  life  of  the  fly.  How  long  such  a  fly  may  retain  its  power 
to  infect  is  yet  a  question,  though  it  has  been  found  by  the  Sleeping 
Sickness  Commission  to  be  at  least  three  months.  The  duration  of  the 
life  of  the  tsetse  fly  has  only  been  observed  upon  specimens  in  captivit}^, 
but  it  is  probable  that  it  is  about  four  to  six  months. 

Control. — Measures  looking  to  the  control  of  the  breeding  of  the 
flies  are  limited  practically  to  exclusion  owing  to  the  fact  that  the  larval 
period  is  passed  within  the  body  of  the  female,  hence  offers  no  opportu- 
nity for  attack  through  sources  of  larval  food  supply.  The  fact  that 
tsetse  flies  seek  the  vicinity  of  water  courses  surrounded  by  wooded 
areas  may  be  taken  advantage  of  in  excluding  them  from  locations  of 
settlement.  With  a  view  to  this  it  has  been  recommended  that  clearings 
be  made  over  an  area  of  six  hundred  to  eight  hundred  yards  at  some 
distance  from  streams  of  water,  the  water  supph'  l^eing  obtained  from 
wells.  The  difficulties  presented,  however,  in  the  control  of  the  fly  are 
numerous  and  in  many  features  seem  unsurmountable.     The  ultimate 


THE  FLIES 


47 


solution  of  the   problem   probably  lies  in  innnunization   against   the 
tsetse  fly  diseases,  as  to  which  little  progress  has  yet  been  made. 

Family  V.    Hippoboscid^ 

Diptera  (p.  23). — The  body  is  flattened.  Wings  are  present  or  absent. 
The  wing  veins  are  crowded  toward  the  anterior  margin.  The  head  is 
sunk  into  an  emargination  of  the  thorax;  the  antennae  inserted  in  pits 
near  mouth;  mouth  j:)arts  adapted  for  piercing  and  sucking  blood. 
The  legs  are  stout,  terminated  by  .strong  claws.  The  abdomen  is  large 
and  sacular  with  segments  indistinct. 

The  Hippoboscidse  are  pupipai'ous,  the  eggs  being  hatched  and 
nearly  the  whole  of  the  larval  stage  passed  within  the  body  of  the  parent. 
The  larvae  are  extruded  only  when  nearly  ready  to  transform  into  pupae. 

All  are  parasitic  upon  birds  and  mannnals.  Hippohosca  equina  is  a 
winged  species  occurring  upon  the  horse,  and  known  in  England  as  the 
forest  fly. 

^NIelophagus  Ovixus 

The  sheep  "tick." — Hippoboscidae  (p.  47).  Three-si.xteenths  to  one- 
quarter  of  an  inch  in  length.  The  color  reddish  or  grayish  brown. 
The  wings  and  halteres  are  ab- 
sent. The  head  is  small  and 
sunken  into  the  thorax;  ab- 
domen large,  sac-like,  and 
covered  with  short  spines 
(Fig.  25). 

Life  History. — INLatured  lar- 
vs  are  extruded  from  the  body 
of  the  female  and  at  once  enter 
upon  their  pupation,  the  red- 
dish brown  pupae  adhering  to 
the  wool  fibers.  The  pupal 
stage  occupies  three  to  six 
weeks  according  to  season  and 
temperature,  the  shorter  jieriod 
occurring  during  the  sunnner. 
At  sexual  maturity  the  deposi- 
tion of  pupae  begins,  each  fe- 
male depositing  from  eight  to 
ten.  Probably  the  life  of  the 
tick  will  not  exceed  four  to  five 
months. 

Occurrence. — The  sheep  tick  is  distributed  over  all  parts  of  the 
workl  where  sheep  are  kept.    Its  parasitism  is  continuous,  the  pupiparous 


Fig.  25. — Melophagus    ovinus    (from    photo- 
graph of  mounted  specimen,  by  Hoedt). 


48  PARASITES  OF  THE  DOMESTIC  ANII^L\LS 

habit  of  bringing  forth  its  3'oung  adapting  it  to  spend  its  whole  hfe  upon 
the  host  from  which  it  never  migrates  miless  to  attach  to  another  animal 
of  the  same  species.  It  is  probable  that  this  migration  occurs  principally 
at  the  time  of  shearing  when  the  ticks  leave  the  sheared  sheep  and  crawl 
upon  the  lambs.  Off  the  host  the  ticks  will  not  survive  longer  than  a 
few  days,  probably  all  will  be  dead  within  a  week. 

Effect. — All  breeds  of  sheep  are  ahke  subject  to  attack,  the  presence 
of  the  "tick,"  or  "louse,"  as  it  is  commonly  called,  and  the  injmy  which 
it  causes,  being  a  matter  of  common  knowledge  to  sheep  breeders.  Sheep 
are  not  materially  affected  by  a  few,  but  if  in  larger  numbers,  their 
presence  will  be  manifested  by  rubbing,  scratching,  and  biting  at  the 
fleece.  Loss  of  flesh  and  general  unthriftiness  will  occur  in  badly  in- 
fested animals.  Where  the  ticks  are  prevalent  lambs  may  be  attacked 
by  large  numl^ers  at  shearing  time,  in  which  condition  many  will  die 
unless  promptly  relieved. 

Treatment. — In  the  winter  months,  when  the  long  wool  will  not 
permit  of  other  treatment,  the  ticks  may  be  greatly  reduced  in  number 
by  the  use  of  pyrethrum  powder  which  should  be  freel}^  blown  deep  into 
and  upon  the  fleece  over  all  parts  of  the  body.  The  most  effectual  treat- 
ment is  best  applied  after  shearing  and  consists  of  the  application  by 
dipping  or  as  a  wash  of  such  remedies  as  creolin,  zenolium,  lysol,  or 
cresol,  used  in  two  to  three  per  cent,  strength.  Decoction  of  tobacco, 
in  strength  of  three  to  four  per  cent,  is  also  used,  but,  to  avoid  danger  of 
nicotine  poisoning,  should  not  be  applied  to  all  parts  of  the  bodj^  at  once. 
Kerosene  emulsion,  which  has  a  wide  range  of  usefuhiess  in  the  treat- 
ment of  external  parasites,  is  another  of  the  numerous  dips  resorted  to 
in  this  connection.  The  emulsion  may  be  made  either  with  milk  or  soap 
according  to  the  following  formulae : 

Milk  emulsion. — To  one  part  milk  add  two  parts  kerosene  and  churn 
by  a  force  pump  or  by  other  means  of  agitation.  Dilute  the  resulting 
emulsion  with  eight  to  ten  times  its  bulk  of  water. 

Soap  emulsion. — Dissolve  one-half  a  pound  of  hard  soap  in  one  gallon 
of  hot  water  and,  while  still  at  near  boiling  point,  add  two  gallons  of 
kerosene.  Emulsify  b}^  use  of  force  pump  or  other  means  of  agitation. 
Dilute  one  part  emulsion  with  eight  or  ten  parts  water. 

These  emulsions  maj^  be  used  in  the  proportions  given  as  a  spray, 
wash,  or  dip. 

None  of  these  dips  will  kill  the  pupae,  and,  therefore,  keepmg  in 
mind  the  life  histor}'  of  the  parasite,  the  treatment  should  be  re- 
peated in  about  twenty-four  daj^s.  If  the  dipping  has  been  done  in 
the  cooler  weather  of  autumn,  this  interval  should  be  accordingly 
prolonged. 

As  the  movement  of  the  ticks  from  the  sheep  to  the  lambs  takes  place 
principally  at  the  time  of  shearing  when  the  insects  are  removed  from 


THE  FLIES  49 

their  host  with  the  fleece,  it  is  well  at  this  time  to  keep  the  lambs  at 
some  distance  from  the  stored  wool.  This  precaution  should  be  ob- 
served for  at  least  a  week  from  the  time  of  shearino-,  at  the  termination 
of  which  period  the  ticks  which  have  l)een  removed  with  the  wool  will 
be  dead. 


CHAPTER  VI 

DIPTEROUS  LARV^ 

Flesh  flies,  blowflies,  botflies. — The  larvae  of  these  flies  produce  a 
form  of  parasitism  to  which  the  term  myasis  (also  myiasis,  and  myiosis) 
is  appHed.  Various  forms  of  myasis  are  recognized  according  to  the 
location  of  the  larvae,  as  cutaneous,  muscular,  nasal,  gastric,  and  intes- 
tinal. With  certain  species,  as  those  of  the  family  CEstridse,  or  true 
botflies,  the  larval  parasitism  is  obligate  upon  or  within  a  living  host 
anhnal,  while  the  larvae  of  the  flesh  and  blowflies  of  the  family  Muscidae 
may  attack  either  living  or  dead,  usually  decomposing,  tissue. 

Chrysomyia  Macellaria 

Compsomyia  macellaria;  Cochliomyia  macellaria,  Screw  worm  fly. — 
Muscidae  (p.  37).  Three-eighths  to  half  an  inch  in  length;  color  bluish 
green  with  metallic  reflections.  There  are  three  longitudinal  black 
stripes  upon  the  thorax.  The  head  is  reddish  or  yellowish  brown; 
thorax  and  abdomen  covered  with  stiff  black  hairs  (Fig.  26) . 

The  eggs  are  about  1  mm.  in  length,  white  and  cylindrical.  They 
are  deposited  in  masses  of  three  hundred  to  four  hundred  upon  dead 
and  decaying  flesh  and  upon  wounds,  sores,  or  within  the  nostrils  or 
other  natural  mucous  openings  of  man  and  lower  animals.  Hatching 
may  occur  in  from  one  to  twelve  hours  from  the  time  the  eggs  are 
deposited. 

The  larvae  are  white,  apodal,  slender,  and  quite  active.  The  head 
and  segments  are  provided  with  spines  which  facihtate  their  burrowing 
into  the  living  or  putrefying  flesh  upon  which  they  feed,  a  habit  which 
gives  to  the  mature  insect  its  common  name  of  screw  worm  fly.  Under 
most  favorable  conditions  the  full  larval  growth  is  reached  in  three  days, 
at  which  time  they  may  be  half  an  inch  or  more  in  length.  When  mature 
they  leave  the  flesh  upon  which  they  have  been  feeding  and  bury  them- 
selves in  the  earth  near  by,  in  which  location  they  enter  upon  pupation. 

The  pupae  are  6  to  9  mm.  in  length,  somewhat  barrel-shaped,  and 
dark  brown  in  color.    The  pupal  stage  may  last  from  six  to  twelve  days. 

Occurrence  and  Effect. — The  screw  worm  fly  is  widely  distributed, 
being  found  throughout  North  and  South  America.  In  the  United 
States  it  is  especially  abundant  in  the  South,  where  it  is  responsible  for 
the  most  serious  cases  of  human  myasis  occurring  in  this  country.  It 
begins  to  attack  in  June,  but  has  its  greatest  period  of  activity  in  the 


DIPTEROUS  LARVAE 


51 


three  months  which  follow.  In  its  attacks  upon  man  it  usually  deposits 
its  eggs  in  the  nostrils  or  mouth  while  the  individual  is  sleeping.  It  is 
especially  attracted  if  the  parts  are  unclean,  as  from  the  discharge  of 
nasal  catarrh  or  collections  of  vomit  about  the  lips.  Persons  in  a  drunken 
stupor  are  especially  liable  to  attack.  For  the  same  reason  open  sores 
contaminated  by  collections  of  pus  or  blood  are  equally  attractive  to  it. 

The  fl3''s  greatest  injury  as  a  pest  to  domestic  animals  in  the  United 
States  occurs  in  the  Southwest,  where  cattle  are  the  greatest  sufferers 
from  its  ravages.  In  these  animals  the  flies  are  attracted  to  wounds  of 
operations,  such  as  dehorning,  branding,  castrating,  etc.,  and  to  injuries 
such  as  may  result  from  hooking  or 
barbed  wire.  In  fact  any  open 
wound  or  exposed  mucous  mem- 
brane, especially  if  soiled  with  an 
odorous  discharge,  is  a  favorite  seat 
of  attack. 

Upon  hatching,  the  larvae  at  once 
proceed  to  attack  the  tissues  and 
maA'  rapidly  produce  a  serious  de- 
struction and  mutilation.  Thej^  grow 
rapidly  as  they  consume  the  tissues 
adjacent  to  them,  and  in  locations, 
as  parts  of  the  limbs  where  there  is 
little  fleshy  covering,  the  bones  may 
be  laid  bare. 

Protection.-As  most  of  the  fatal  ^^^  26.-Compsomyia  macellaria-en- 
cases  of  myaslS  m  man  from  this  larged  (after  Osborn,  from  Francis,  Bui. 
cause  are  due  to  deposition   of  eggs   ^o.  5,  Bureau  of  Entomology,  U.  S.  Dept. 

in  the  nostrils  while  the  person  is  °  "  ^^ 

sleeping,  the  first  measure  of  precaution  is  to  protect  from  attack  by  the 
use  of  netting.  Those  sleeping  out  of  doors  in  infested  regions  are  most 
exposed,  but  sleeping  rooms  should  also  be  thoroughh'  screened.  Open 
jiores  and  wovmds  should  of  course  be  kept  free  from  collecting  discharge 
and  covered  with  clean,  drj'  dressing.  The  same  precautions  as  to 
(ileanliness  of  wounds  and  exposed  mucous  membranes  applies  to  domes- 
tic  animals.  The  vulvae  of  cows  recently  fresh,  especially  if  there  has 
been  a  retention  of  the  placenta,  and  the  navels  of  calves  offer  favorite 
points  for  attack  and  should  particularly  be  guarded. 

Treatment. — Where  sores  and  exposed  mucous  membranes  have 
already  become  infested  with  worms  a  disinfecting  wash,  such  as  a  one 
to  three  per  cent,  solution  of  carbolic  acid,  should  be  used.  For  injection 
into  regions  where  the  maggots  have  penetrated,  the  injection  of  carbolic 
acid  or  creolin  in  about  five  per  cent,  strength  will  destroy  worms  with 
which  it  comes  in  contact.    Chloroform  diluted  to  a  strength  of  about 


d 


52  PARASITES  OF  THE  DOMESTIC  ANIMALS 

twenty  per  cent,  is  also  recommended  for  this  purpose.  An  ordinary 
machinist's  oiler  affords  a  practical  method  of  applying  such  agents.  It 
has  the  advantage  of  deep  application  without  waste  of  the  material. 
For  deeply  infested  wounds  a  final  packing  of  oakum  and  oil  of  tar  should 
be  applied,  and  this  should  be  covered  by  a  protective  dressing  of  tar 
and  oakum  as  a  prevention  from  further  attack. 

Sarcophaga  SaRRACENIvE 

A  flesh  fly.— Muscidse  (p.  37).  In  markings  somewhat  similar  to  the 
house  fly,  but  considerably  larger.  The  general  color  is  light  gray;  eyes 
reddish  brown.    Body  spiny. 

The  female  deposits  larvae  upon  fresh  meat,  or  in  the  wounds  of  living 
animals.     Under  favorable  conditions  the  larval  stage  is  completed  in 

about  six  days.  The 
mature  larvae  crawl  to 
a  convenient  shelter 
where  they  undergo  a 
.-     A,  .  .     •     wi    fl    1  fl    /c         I       >      pupation   from    which 

Fig.  2/. — Metamorphosis  of  the  flesh  fly  (Sarcophaga) :  ,          ,    ,       •            •     r- 

a,  eggs;b  ,  young  larva  just  hatched;  c,  d,  full-grown  larvae;  the  adults  ISSUC  Ul  trom 

e,  pupa;  f,  imago  (after  Ortoii,  by  Dodge;  Copyright,  1894,  twelvC        to       fourteen 

by  Harper  &  Brothers) .  ^j^,^,^  (p.g_  27) . 

Protection. — The  flesh  flies  are  of  world-wide  distribution,  and  are 
of  most  importance  as  they  affect  fresh  meats  in  the  household  or  meats 
in  storage.  As  a  protection  in  such  cases  the  flies  should  be  screened  off 
at  some  distance,  as  larvae  which  have  been  deposited  in  the  vicinity  of 
meat  will  crawl  to  it,  though  it  may  not  be  accessible  to  the  flies. 

To  prevent  their  attack  upon  wounds,  the  same  general  procedure 
may  be  adopted  as  recommended  for  the  preceding  species. 

Calliphora  Vomitoria 

Blowfly. — Muscidse  (p.  37).  Somewhat  larger  than  house  fly;  eyes 
brownish  in  color;  abdomen  bluish  green  with  metalic  luster  and  usually 
pollinose. 

The  eggs  are  oval,  white  in  color,  and  are  deposited  upon  decomposing 
animal  and  vegetable  matter  and  in  wounds  of  animals.  Hatching  may 
occur  in  from  a  few  hours  to  one  or  two  days,  the  shorter  periods  occurring 
in  hot  weather.  After  from  three  to  nine  days  of  feeding,  the  matured 
larvae  seek  the  ground,  become  buried  for  a  short  distance,  and  in  this 
location  enter  upon  their  stage  of  pupation.  The  time  required  for  the 
entire  life  cycle,  including  a  prepupal  period  of  several  clays,  may  be 
from  two  to  five  weeks,  depending  greatly  upon  temperature.  Under 
ordinary  conditions  it  would  piobably  occupy  al^out  three  weeks. 

The  blowfly  agrees  with  the  flesh  fly  in  its  habits,  with  the  exception 


DIPTEROUS  LARVyE  53 

that  it  deposits  eggs  instead  of  living  larvae.  After  hatching  the  manner 
of  attack  and  the  effect  upon  infested  meat  and  wounds  is  much  the 
same  and  calls  for  the  same  treatment. 

Family  VI.  CEstrid^ 

Diptera  (p.  23).  Botflies,  warble  flies.  The  head  is  large,  bearing  two 
faceted  eyes  widely  separated,  antennae  short  and  sunken  into  pits  in 
the  front  of  the  head.  The  mouth  parts  are  rudimentary,  most  all  of  the 
flies  living  in  the  adult  stage  without  food.  The  body  is  heavy  and 
somewhat  hairy.    The  coloration  is  usually  inconspicuous. 

The  larvai  are  thick  and  twelve-segmented,  the  first  two  segments 
not  alwaj^s  distinctly  separated.  There  is  no  demarcation  into  body 
regions,  only  a  cephalic  and  anal  end  can  be  distinguished.  The  body- 
segments  are  frequently  provided  with  rows  of  spines.  Buccal  hooks 
may  or  may  not  be  present.  Tracheal  openings  are  at  the  posterior 
extremity. 

The  larvae  are  parasitic  in  the  stomach  and  intestines,  mucous  mem- 
branes, subcutaneous  connective  tissue,  nasal  passages,  and  sinuses  of 
facial  bones  of  mammals ;  other  parts  are  also  invaded  by  their  migrations. 
When  completely  developed  the  larva  leave  these  locations  in  the  host 
and  pass  to  the  ground  where  they  enter  the  pupal  stage. 

The  flies  of  the  family  QCstridae  are  of  world-wide  distribution. 

Gastrophilus  intestinalis  {G.  equi).  Qilstridae  (p.  53).  The  horse 
botfly  (Fig.  28,  h).  The  body  of  the  female  is  one-half  to  five-eighths  of 
an  inch  in  length  and  is  very  hairy.  The  head,  thorax  and  abdomen  are 
brown.  The  wings  are  transparent  with  dark  spots,  those  near  the  center 
passing  entirely  across  the  wing  transversely.  The  abdomen  is  rather 
long  and  tapers  to  a  point.  In  the  males,  which  are  rarely  seen,  the 
abdomen  is  light  brown  or  yellow,  and  it  is  not  tapering.  In  other  re- 
spects the  males  closely  resemble  the  females. 

The  larvae  (Fig.  28,  c,  d  and  g)  when  full  grown  are  about  three- 
fourths  of  an  inch  in  length.  At  the  head  extremity  are  two  buccal 
hooks  by  which  attachment  is  made  to  the  gastric  mucosa  (Fig.  28,  e). 
The  body-segments  are  bordered  by  short  spines  (Fig.  28,  d). 

Habits. — Like  other  members  of  the  Q^stridae,  the  horse  botfly  at 
matuiity  is  extremely  active,  flying  chiefly  during  the  warmest  and 
bi-ightest  days  of  the  summer,  and  generally  frequenting  pastures  in 
the  vicinity  of  woods.  It  is  the  habit  of  the  female  to  hover  near  the 
horse  with  its  long,  pointed  abdomen  bent  downwaid  and  forward.  The 
fly  then  darts  toward  the  horse,  deposits  its  egg,  retreats,  and  again 
hovers  until  ready  to  repeat  the  operation.  The  eggs  (Fig.  28,  a  and  b) 
are  yellow  in  color,  about  one-sixteenth  of  an  inch  in  length,  and  tapering 
toward  the  attached  end,  the  free  end  being  provided  with  an  operculum 
which  is  set  obliquely  and  gives  to  this  end  somewhat  of  an  obliquely 


54 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


cut  off  appearance.  The}'  are  generally  deposited  upon  the  hairs  of  the 
anterior  parts  of  the  body,  as  upon  the  forelegs,  breast,  shoulders,  and 
under  side  of  the  body,  regions  which  are  most  readily  reached  by  the 
lips  of  the  horse.  It  is  not  uncommon,  however,  for  eggs  to  be  attached 
to  the  sides  of  the  neck,  lower  jaw,  cheeks,  mane,  and  other  parts,  the 
larvae  in  such  cases  reaching  the  mouths  of  horses  by  their  licking  or 
nipping  at  each  other. 

Life  History. — The  eggs  are  deposited  rapidly  with  their  free  ends 
down,  and  adhere  to  the  hairs  by  a  viscid  substance  which  quickly  dries 


Fig.  28 — Gastrophilus intestinalis:  a,  egg — enlarged;  b,  egg — natural  size;  c,  young  larva; 
d,  young  larva — much  enlarged,  showing  spiny  armature;  e,  oral  hooks;  f,  body  spines;  g, 
full-grown  larva — twice  natural  size;  h,  adult  female  (after  Osborn,  Bui.  No.  5,  Bureau  of 
Entomology,  U.  S.  Dept.  of  Agr.). 

and  gives  them  a  firm  attachment.     At  this  time  they  contain  larvae 
which  have  undergone  a  more  or  less  advanced  development. 

Observations  upon  the  botflies  during  recent  years  have  been  some- 
what disturbing  to  conclusions  formerly  held  and  apparently  necessitate 
a  certain  revision  of  the  life  histories  which  have  generally  been  given  for 
them.  According  to  the  observations  of  Roubaud  (1917)  upon  Gas- 
trophilus intestinalis,  the  eggs  of  the  fly  do  not  open  spontaneously,  and 
the  larvae  may  not  escape  from  them  for  several  weeks.  The  opening 
of  the  operculum  and  freeing  of  the  larva  probably  occurs  when  the 
horse  rubs  an  itching  or  irritated  area  with  his  nose  or  bites  it  with  his 
teeth,  the  horse  rarely  hcldng  itself.  By  experiments  with  bot  larvae  on 
guinea-pigs  Roubaud  demonstrated  that  when  the  hatched  larva  is 
brought  in  contact  with  the  buccal  mucosa  it  at  once  burrows  into  this 
membrane  and  lies  parallel  to  its  surface.  In  two  or  three  days  it  dis- 
appears, but  he  notes  that  one  was  seen  traveling  along  the  side  of  the 


DIPTEROUS  LARV.E  55 

tongue  for  nine  daj's,  during  which  time  it  grew  to  three  times  its  first 
dimensions.  Before  leavmg  the  buccal  mucosa  the  larvae  probably 
undergo  a  molt  and  then  proceed  to  the  stomach.  These  observations 
indicate  that  the  larvae  of  the  botfly  escape  from  the  eggs  when  the  horse 
bites  at  his  skin  or  rubs  it  with  his  lips,  and  that  the}'  burrow  into  the 
buccal  mucosa  where  they  undergo  a  degree  of  development  before 
passing  to  the  stomach. 

Within  the  stomach  cavity  the  larva  fixes  itself  to  the  walls  bj-  its 
buccal  hooks.  Later  the  head  becomes  deepl}'  mserted  into  an  alveolus 
which  is  formed  mider  the  influence  of  the  irritation  to  the  mucosa.  In 
this  position  the  larva  feeds  upon  the  tissue  juices  and  the  products  of 
the  irritation  which  it  sets  up,  becoming  fully  grown  in  about  ten  months. 
The  period  of  larval  development  usually  terminates  from  May  to 
August,  more  especially  in  June,  due  to  the  fact  that  the  deposition  of  the 
eggs  occurs  most  actively  in  the  month  of  August.  At  this  time  the 
larva  becomes  detached  from  the  gastric  mucosa,  passes  to  the  intestines, 
and  with  the  mtestinal  contents  leaves  the  body  of  its  host. 

The  change  into  the  pupal  stage  is  made  either  in  the  horse  manure 
or  after  the  larva  has  burrowed  for  a  short  distance  into  the  ground. 
At  the  termination  of  pupation,  which  lasts  from  four  to  six  weeks,  the 
matured  fly  creeps  out,  and,  after  fertilization  by  the  male,  proceeds  to 
deposit  ova  for  another  generation. 

Tabular  Review  of  Life  History  of  Gastrophilus  Intestinalis 
L  Adult  Flv.— (August.) 

I 

2.  Eggs. — Attached  to  hairs  of  horse  (Aug.  and  Sept.); 

I  approximately  2  weeks. 

3.  Young  Larvae. — Upon    or    within    mucosa    of    horse's 

I  mouth. 

4.  Larvae  (Bots). — Attached  to  wall  of  horse's  stomach. 

I  Stages  3   and  4   approximateh'   10 

I  months. 

5.  Pupae. — Free  (June) ;  approximately  6  weeks. 

6.  Adult  Fly.— (August.) 

Effect. — The  degree  of  injury  due  to  the  presence  of  the  larvae  of 
this  botfl}'  will  depend  upon  their  number  and  location.  .That  the 
stomach  may  be  invaded  by  a  considerable  number  of  bots  without 
apparent  disturbance  to  this  organ  is  probably  due  to  the  fact  that  they 
most  commonly  attach  to  the  esophageal  portion,  this  region  of  the 
horse's  stomach  havhig  a  less  important  part  in  the  function  of  digestion 


56  PARASITES  OF  THE  DOMESTIC  ANIMALS 

than  that  toward  the  pyloris.  Where  they  occupy  the  glandular  right 
half,  especially  if  in  large  numbers,  they  interfere  with  the  digestive 
secretion  and  its  proper  contact  with  the  gastric  contents.  In  excep- 
tional cases  they  may  be  sufficiently  numerous  about  the  pyloris  to 
form  an  obstruction  to  the  passage  of  food  material  into  the  small  intes- 
tine; or  even  the  duodenum  itself  may  be  invaded.  Under  these  latter 
conditions  the  larvae  bring  about  nutritive  disturbances  and  may  cause 
attacks  of  acute  indigestion  with  its  accompanying  manifestations  of 
pain.  When  we  consider,  however,  the  large  number  of  horses  essentially 
harboring  the  larvae  of  the  horse  botfly,  as  indicated  by  the  widespread 
prevalence  of  the  insect,  we  must  conclude  that  they  are  comparatively 
inoffensive,  for  in  most  cases  there  is  an  entire  absence  of  any  apparent 
disturbance  and,  with  the  exception  of  the  voiding  of  the  bots,  nothing 
during  the  life  of  the  animal  which  would  lead  to  suspicion  of  their 
presence. 

Treatment. — The  larv«  of  Gastrophilus  are  so  resistant  that  treat- 
ment having  in  view  their  destruction  or  expulsion  has  been  generally 
unsatisfactory.  Such  agents  as  preparations  of  tar,  benzine  and  turpen- 
tine, which  are  sometimes  used  for  this  purpose,  add  irritation  to  an 
already  irritated  gastric  mucosa  and,  for  this  reason,  in  connection  with 
their  general  ineffectiveness,  the  advisability  of  their  use  is  questionable. 
AVhere  the  presence  of  the  bots  in  sufficient  numbers  to  cause  disturbance 
to  the  health  of  the  animal  is  suspected,  gastric  irritation  may  be  allayed 
to  some  extent  by  feeding  mucilaginous  materials,  such  as  flaxseed  meal. 
Hay  in  such  cases  is  best  fed  chopped,  and  a  substantial  nutritive  diet 
should  be  looked  to  as  compensatory  to  the  loss  of  nutriment. 

A  treatment  recommended  by  Peroncito  and  Bosso  (1894)  consists 
in  the  administration  of  carbon  bisulphide  to  adult  horses  in  gelatin 
capsules,  each  containing  8  to  12  grams  (2  to  3  drams).  After  fasting  for 
twelve  to  twenty  hours,  the  horse  is  given  one  capsule ;  after  one  hour  a 
second  capsule  is  given,  and  after  another  hour  a  third.  As  carbon 
bisulphide  is  strongly  irritant,  care  should  be  taken  in  the  administration 
of  the  capsules  that  the  cap  does  not  become  detached  and  that  they  do 
not  become  crushed  in  the  mouth. 

In  so  far  as  clinical  observation  can  determine  the  presence  of  bots,  or 
lead  to  the  conclusion  that  a  remedy  has  caused  the  expulsion  of  any 
considerable  number  of  them  in  proportion  to  the  infestation,  this  treat- 
ment is  said  to  be  generally  satisfactory.  It  seems  reasonable  to  con- 
clude that  an  agent  sufficiently  active  to  cause  the  expulsion  of  these 
robust  larvae  from  their  secure  attachment  would  have  a  severely  irritant 
effect  upon  the  gastric  mucosa,  though  this  membrane  of  the  stomach 
appears  to  have  a  greater  tolerance  for  such  assaults  than  that  of  other 
regions  of  the  alimentary  tract. 


DIPTEROUS  LARV.E  57 

Gastrophilus  Hemorrhoidalis 

The  red-tailed  botfly.— CEstridse  (p.  53).  Somewhat  smaller  than 
6'.  intestinalis.  Dark  brown  color,  yellowish  hairs  upon  the  face;  trans- 
verse black  band  upon  thorax.  The  abdomen  is  covered  with  fine  hairs 
which  in  the  middle  are  dai-k  and  posteriorly  oranp;e-red.  The  wings  are 
clear. 

This  species  of  horse  botfl}^  is  found  in  common  with  (t.  intestinalis  in 
North  America  and  Europe. 

The  females  attach  their  ova  to  the  hairs  of  the  horse,  preferably 
those  about  the  lips.  The  hatched  larvae  cause  an  irritation  which 
impels  the  horse  to  pass  its  tongue  about  its  lips,  thus  carrying  the 
parasite  into  the  mouth.  In  other  respects  its  life  history  is  essentially 
the  same  as  that  of  G.  intestinalis.  The  larvae  differ  from  those  of  the 
latter  in  being  somewhat  smaller  and  in  their  dark-red  color.  There  is 
also  some  difference  in  their  habitat  in  that  they  attach  usually  to  the 
pyloric  portion  of  the  stomach,  and  when  fully  developed  pass  on  to  the 
rectum  where  they  remain  for  some  time,  assuming  a  green  color  before 
l)eing  voided. 

Effect. — The  presence  of  the  larvae  of  this  fly  in  considerable  num- 
bers in  the  folds  of  the  i-ectal  mucous  membrane  may  cause  an  anno\'ing 
irritation,  inducing  violent  efforts  at  defecation.  Such  cases,  however, 
are  extremely  rare,  and,  as  a  rule,  little  or  no  evidence  is  given  by  the 
animal  of  their  presence. 

Gastrophilus  nasalis. — (EstricUe  (p.  53).  This  species,  connnonly 
called  the  chin  fly,  is  about  1  cm.  ('Vs  of  an  inch)  in  length.  The  body  is 
hairy  and  yellowish  red  in  color.    The  wings  are  without  spots. 

Law  describes  the  larvae  as  "furnished  with  a  row  of  spines  on  each 
ring  from  the  second  to  the  ninth  on  the  dorsal  surface,  and  as  far  as  the 
tenth  on  the  ventral.  There  is  an  unarmed  part  in  the  center  of  the 
eighth  and  ninth  rings  on  the  dorsal  surface." 

The  fly  deposits  its  eggs  about  the  lips  and  nostrils.  Th<>  larvae  attach 
to  the  mucosa  of  the  upper  part  of  the  small  intestine. 

Fitch  states  (1918),  as  to  New  York  State,  that  from  examination  of 
the  larvae  it  would  seem  that  Gastrophilus  nasalis  is  quite  as  frequent 
as  G.  intestinalis. 

Hypoderma  Lixeata  axd  H.  Bovis 

The  ox  botflies;  warble  flies  (Fig.  29).— CEstridae  (p.  53).  Hypodernia 
lineata  is  about  five-eights  of  an  inch  m  length.  The  general  color  is 
black;  body  more  or  less  covered  with  hairs.  The  front,  sides,  and  back 
of  the  head,  sides  of  thorax,  and  last  segment  of  the  abdomen  are  covered 
with  long  yellowish  white  hairs. 

This  fly  is  found  in  all  parts  of  the  United  States,  but  more  especially 


58 


PARASITES  OF  THE  DOMESTIC  ANIIVLVLS 


ill  the  southern  portion  as  far  north  as  Illinois,  Iowa,  and  Nebraska. 
It  makes  its  appearance  in  the  spring  or  earty  summer  and  is  at  once 
attracted  to  cattle,  depositmg  its  eggs  on  the  hairs,  frequently  upon 
those  about  the  heel,  a  habit  which  gives  to  the  ^y  its  southwestern 
name  "heel-fl}'." 

The  entire  length  of  the  egg  is  1  mm.  and  its  width  0.2  mm.  In  color 
it  is  a  yellowish  white.     The  eggs  are  firmly  attached  to  the  hairs  by 

means  of  a  clasping  projec- 
tion which  connects  with 
the  egg  proper  by  a  short 
pedicle  (Fig.  31).  Usually 
they  are  deposited  upon 
the  hairs  in  groups  of  four 
to  six. 

Hypoderma  Bovis. — (Es- 
tridse  (p.  53).  This  species 
is  commonly  referred  to  as 
the  European  warble  fl.y, 
though  it  occurs  also  in 
Canada  and  the  United 
States.  It  is,  in  fact,  said 
to  be  more  common  in  some 
pai-ts  of  this  country  than 
H.  lineata.  Its  length,  ex- 
clusive of  the  ovipositor,  as 
stated  by  Neumann,  is  13 
to  15  mm.  {}/2  to  %  of  an 
inch),  which  is  1  to  2  mm. 
longer  than  H.  lineata.  The 
general  color  is  black,  face 
gra}^;  abdomen  black;  head, 
thorax,  and  abdomen  hairy. 
The  hairs  from  the  base  to  the  tip  of  the  abdomen  vary  in  color  from 
white  or  3^ellow  to  black;  orange  red  at  posterior  third.  The  legs  are 
black,  yellow  at  their  terminations;  wings  somewhat  brown. 

As  to  the  differentiation  of  the  larvse  of  these  two  species,  Herms 
writes  as  follows:  "The  life  history  of  the  two  species  is  very  similar. 
The  larvse  are  different  enough  to  distinguish  them  readily.  The  fully 
grown  larva  of  H.  bovis  is  longer,  27  to  28  mm.,  H.  lineata  about  25  mm. 
The  two  species  are  distinguished  on  the  basis  of  their  spiny  armature. 
In  H.  lineata  each  segment  of  the  larva  is  provided  with  spines  except 
the  last,  the  ring  upon  which  the  stigmata  are  located,  while  in  H.  bovis 
all  except  the  last  two  are  armored." 

Life  History. — Dr.  Cooper  Curtice,  from  his  researches  in  1890, 


Fig.  29. — Hj^poderma  lineata  (after  Osborn,  from 
Insect  Life,  Bui.  No.  5,  Bureau  of  Entomology,  U.  S. 
Dept.  of  Agr.). 


DIPTEROUS  LARV.E 


59 


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J 

\ 

concluded  that  the  larv£e  of  Hypoderma  lineata  are  taken  into  the  mouths 

of  cattle  by  licking  the  parts  where  the  eggs  are  attached,  the  eggs  under 

this     influence    hatching    at    once.     

From  the  mouth  the  larva,  according 

to  this  investigator,  is  carried  to  the 

esophagus,    the    walls    of  which    it 

penetrates.     While    lodged    in    the 

esophagus  it  molts,  and  the  body  be- 
comes ciuite  smooth.     For  a  period 

of    several     months     thereafter    it 

wanders     through     the     connective 

tissue  beneath  the  skin  or  between 

muscles,   and    ultimately  reaches   a 

point  beneath  the  skin  of  the  back. 

Here  the  larva  again  molts  and  the 

spiny  processes   reappear   upon   its 

body.     It  now  cuts  a  small  opening 

through    the    skin,    and    places    its 

anal  spiracle  near  this  orifice  in  order  to  get  air.     In  this  location  the 

larva  lives  upon  the  products  of  the  inflammation  which  its  presence 

sets  up,  such  as  bloody  serous  exudate  and  pus.    It  now  develops  rapidly 

and  again. molts,  at  which  time  the  grub  is  fat,  yellowish-white  in  color, 
and  an  inch  or  more  in  length.  Reaching  the 
maturit}^  of  its  larval  period  (Fig.  32,  g  and  i), 
which  lasts  about  ten  months,  it  works  its  wa}' 
out  of  the  orifice  at  the  summit  of  the  tumor 
and  drops  to  the  ground,  into  which  it  may 
burrow  for  a  short  distance.  Here  it  enters 
upon  the  pupal  stage,  the  hardened  larval  skin 
becoming  the  protecting  case  for  the  pupa 
within.  After  about  four  to  six  weeks  of 
pupation  the  adult  fly  escapes  by  pu.shing  off 
the  cap  at  the  end  of  the  pupal  case. 

Dr.  Sevmour  Had  wen,   in  notes  on  ''The 


Fig.  30. — Hypoderma  Ijovis  (after  Os- 
born,  from  Brauer,  Bui.  No.  5,  Bureau  of 
Entomology,  U.  S.  Dept.  of  Agr.). 


PfFiG 


T  Life  History  of  Hypoderma  bovis  and  H.  linea- 
turn''  based  on  observations  made  at  Agassiz, 


-Eggs  of  Hypo- 
derma lineata,  showing  clasp- 
like  processes — much  enlarged 
(after  Osborn,  Bui.  No.  5, 
Bureau  of  Entomology,  U.  S. 
Dept.  of  Agr.). 


British  Columbia  (Journal  of  the  American 

Veterinary  Medical  Association,  June,  1917) 

summarizes  as  follows: 

'^Hypoderma  lineatum  lays  its  eggs  as  early 

as  April  15th,  but  the  usual  laying  period 
is  during  the  month  of  May.  At  Agassiz  they  have  never  been  cap- 
tured later  than  May  30th.  Hypoderma  bovis  (Fig.  30)  begins  in  the 
early  part  of  June  and   continues  up  to  the  beginning  of  August. 


60  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Between  the  last  appearances  of  H.  lineatum  and  the  first  of  H.  hovis 
there  is  usually  a  period  of  ten  days  when  the  cattle  are  immune  from 
attack  of  either  species.  H.  hovis  frightens  cattle  much  more  than 
H.  lineatum.  The  eggs  take  about  a  week  to  hatch;  the  larvae  bore 
through  the  skin  in  the  coarser  porous  parts,  taking  several  hours  in  the 
process;  at  this  stage  they  are  rather  less  than  1  nun.  long.  The  lesions 
resulting  from  this  penetration  are  caused  partly  l)y  bacterial  invasion 
and  partly  by  anaphylactic  reactions;  those  produced  by  H.  lineatum 
being  more  severe.  For  the  skin  lesions  I  have  proposed  the  name  of 
hypodermal  rash.  At  this  point  there  is  a  hiatus  in  the  life  history  as  it 
is  not  positively  known  how  the  larvae  reach  the  esophagus,  where  they 
are  subsequently  found,  most  likely  in  the  loose  connective  tissues  under 
the  skin  up  to  the  region  of  the  throat  and  into  the  esophagus  where  the 
muscles  bifurcate.  Passing  down  the  esophagus  they  follow  the  sub- 
mucosa  and  are  almost  always  found  lying  along  the  long  axis  of  the 
canal.  Whilst  in  the  esophagus  small  edematous  swellings  are  found 
surrounding  the  grubs,  these  are  sterile  and  are  anaphylactic  in  char- 
acter, the  exudate  contains  large  numbers  of  eosinophilic  leucocytes  but 
no  pus  cells.  The  earliest  record  made  at  Agassiz  was  on  August  15th, 
when  a  larva  3.4  mm.  was  found  and  several  slightly  larger.  According 
to  Carpenter,  continental  observers  have  found  them  smaller  than  this. 
H.  lineatum  makes  its  appearance  in  the  backs  of  cattle  about  Decem- 
ber 15th  and  H.  bovis  about  a  month  later.  The  larvae  at  this  time  have 
grown  to  about  1.5  cm.  and  are  of  the  same  size  in  the  neural  canal  and 
under  the  skin  which  they  have  just  reached.  At  this  age  it  is  difficult 
to  separate  the  larvae  of  the  two  species,  but  Mr.  F.  C.  Bishopp  has,  I 
believe,  discovered  good  distinguishing  marks  between  the  species.  The 
life  histories  overlap  at  this  period  making  it  difficult  to  follow  the 
migration,  but  in  the  latter  part  of  the  season  (the  middle  of  March) 
the  last  larvae  to  leave  the  gullet  are  at  the  paunch  end.  They  pass  out 
under  the  pleura  and  go  to  the  neural  canal  either  up  the  crura  of  the 
diaphragm  or  up  the  posterior  border  of  the  ribs,  entering  the  canal  by 
the  posterior  foramen,  from  there  they  descend  the  canal  under  the 
dura  mater,  emerge  again  through  the  foramen  and  reach  the  back, 
forming  the  characteristic  swellings  commonly  called  warbles.  The 
larvae  follow  connective  tissue  exclusively  and  no  larvae  have  been  dis- 
covered in  muscular  tissue.  The  mature  larvae  leave  the  animals'  backs 
from  the  early  part  of  the  year  up  to  the  first  days  of  July.  The  periods 
for  the  two  species  have  not  been  fully  worked  out,  but  judging  from 
what  records  we  have  of  the  pupal  period  and  the  time  of  year  the  flies 
are  about,  H.  lineatum  begins  to  emerge  in  February  and  finishes  about 
May  1st.  H.  bonis  begins  about  May  1st  and  ends  approximately  on 
July  1st.  The  average  pupal  period  for  H.  bovis  is  32.5  days  and  for 
H.  lineatum  a  little  less.     The  duration  of  the  life  of  the  flies  is  short 


DIPTEROUS  LARV.E 


61 


re  .      T.  -^ 


62  PARASITES  OF  THE  DOMESTIC  ANIMALS 

seeing  that  they  cannot  feed.  This  hfe  history  apphes  to  Agassiz, 
British  Cohunbia;  doubtless  in  other  countries  variations  will  be  noticed, 
but  the  period  spent  by  the  larvae  within  the  host  must  be  of  the  same 
duration,  seeing  that  animals'  temperatures  are  the  same  the  world  over." 

Effect. — Cattle  seem  to  be  much  annoyed  by  the  attacks  of  these 
flies  in  depositing  their  eggs,  and  in  the  endeavor  to  escape  will  often 
enter  mire  holes  or  injure  themselves  in  other  ways.  Probably  the  most 
important  damage  from  the  insect  is  that  to  hides,  these  being  dis- 
counted from  twenty-five  to  fifty  per  cent,  according  to  the  number  of 
punctures  by  the  grubs. 

Treatment. — Treatment  is  best  applied  in  the  months  of  January 
and  February  when  the  grubs  have  become  sufficiently  developed  that 
the  small  tumors  in  which  they  are  lodged  may  be  felt  by  running  the 
hand  along  the  back  of  the  animal.  The  application  at  this  time  of  a 
little  kerosene  or  mercurial  ointment  to  the  summit  of  the  swelling  will 
destroy  the  grub.  By  March  the  tumors  may  be  distinctly  seen  as 
prominent  lumps  upon  the  skin  of  the  back.  The  orifice  at  the  summit  is 
now  large  enough  to  permit  of  the  forcing  out  of  the  grub  by  careful 
pressure.  Grubs  thus  removed  should  be  at  once  destroyed  to  prevent 
the  possibility  of  their  finding  favorable  conditions  for  development 
into  the  adult  fly. 

QllsTRUS  Ovis 

The  sheep  botfly  (Fig.  33,  1  and  2) .— CEstridce  (p.  53).  About  one- 
half  an  inch  in  length ;  yellowish-gray  color ;  slightly  hairy.  The  abdomen 
is  spotted  with  white  and  yellow;  posterior  portion  covered  with  fine 
hairs.    The  wings  are  transparent. 

Occurrence  and  Life  History. — This  species  is  of  world-wide  dis- 
tribution, and  is  the  most  important  insect  pest  with  which  sheepmen 
have  to  deal.  The  flies  make  their  appearance  with  the  coming  of  warm 
weather  from  early  June  to  July,  like  other  (Estridae,  flying  on  bright 
and  warm  days  and  ceasing  their  activities  about  the  month  of  October. 
The  female,  which  is  difficult  to  observe  owing  to  its  small  size  and  rapid 
flight,  deposits  living  larvae  in  the  nostrils  of  the  sheep.  At  this  time 
the  larva  is  creamy-white  in  color  and  about  one-sixteenth  of  an  inch 
in  length  (Fig.  33,  6).  Later  it  becomes  darker,  and  at  maturitj^  reaches 
a  length  of  about  three-quarters  of  an  inch  (Fig.  33,  4  and  5).  Upon  the 
cephalic  segment  there  are  two  hooklets  the  points  of  which  are  curved 
downward  and  backward.  With  the  aid  of  these  the  larva  at  once  pro- 
ceeds to  work  its  way  upward  through  the  nasal  passages  until  it  reaches 
the  frontal  sinuses  where  it  attaches  by  its  hooklets  to  the  lining  mem- 
brane. Here  it  feeds  upon  mucus  and  serous  exudate  induced  by  the 
irritation  of  its  presence. 

The  larva  remains  in  this  location  about  ten  months,  at  the  end 


c. 

2 

"  1 

^ 

pill 

i 

DIPTEROUS  LARV.E  63 

of  which  tmie,  having  reached  its  larval  maturity,  it  detaches  from  the 
mucous  membrane  and  passes  to  the  nasal  passages  from  which  it  is 
expelled  by  the  violent  sneezing  which  it  excites  in  its  host.  Having 
reached  the  ground,  it  quickly  buries  itself,  contracts  withm  its  smooth 
dark  shell,  and  enters  upon  its  pupal  stage  (Fig.  33,  3).  After  from  four 
to  six  weeks  of  pupation  the  mature  insect  emerges. 

Effect. — Both  sheep  and  goats  suffer  from  the  attacks  of  this  fly. 
Sheep  are  especially  disturbed  by  it,  and  in  their  efforts  to  avoid  its 
attack  will  toss  the  head,  thrust  the  nose  into  the  ground,  or  dash  about 
in  frenzy.  The  grubs  cause  much 
irritation  to  the  sensitive  mem- 
brane which  lines  the  cavities  of 
the  head  both  by  the  booklets 
with  which  they  make  their  at- 
tachment and  by  the  spines  cov- 
ering the  ventral  region.  Further- 
more, if  numerous,  and  the  mucus 
secreted  is  not  sufficient  for  their 
nourishment,  the  grubs  will  feed 
upon  the  membrane  itself.  The 
disturbance  to  the  host  will  be 
manifest  accordmg  to  the  number 
of  grubs  present;  if  there  are  but 
few,  there  may  be  no  more  than 
a  slight  catarrhal  discharge  with 
occasional  sneezuig.  In  heavy 
infestation  there  is  a  profuse 
muco-purulent  nasal  discharge  with  frequent  sneezing  and  tossing  of  the 
head,  the  respiratory  passages  in  some  cases  becoming  so  filled  as  to 
bring  the  animal  to  the  verge  of  suffocation.  The  appetite  is  lost,  and 
emaciation  and  weakness  may  progress  until  there  is  inability  to  rise, 
death  in  such  cases  soon  following. 

Tabular  Review  of  Life  History  of  (Estrus  Ovis 

1.  Adult  Fly. — (June  to  October.) 

I 

2.  Hatched  Embryos. — Deposited  in  nostrils  of  sheep. 

\ 

3.  Larvse. — Attached  to  lining  membrane  of  sinuses  of 

I  sheep's  head.    Stages  2  and  3  approximately 

I  103^  months. 

4.  Pupse. — Free;  approximately  6  weeks. 


Fig.  33. — CEstrus  ovis:  1  and  2,  adult  fly; 
3,  pupa;  4,  full-grown  larva,  dorsal  view; 
5,  same,  ventral  view;  6,  young  larva.  1  and 
2  natural  size,  the  others  enlarged  (after 
Osborn,  from  Riley,  Bui.  No.  5,  Bureau  of 
Entomology,  U.  S.  Dept.  of  Agr.). 


5.  Adult  Fly 


64  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Treatment. — The  location  of  the  grubs  and  the  tortuous  extremity 
of  the  canals  leading  to  such  regions  render  the  application  of  remedies 
looking  to  their  dislodgment  but  partly  effective  at  best.  Benzene  ap- 
plied by  lifting  the  head  and  pouring  a  teaspoonful  into  each  nostril, 
has  been  recommended.  As  one  side  is  treated  the  head  should  be 
held  elevated  and  the  nostril  held  shut  for  half  a  minute.  The  remedy 
is  then  likewise  applied  to  the  other  side.  In  severe  cases  a  few  of  the 
grubs  ma.y  be  dislodged  by  a  feather  dipped  in  turpentine  which  is 
passed  as  far  as  possible  up  the  nasal  passage  and  rotated  so  as  to  apply 
it  to  as  much  of  the  surface  as  can  be  reached.  Valuable  breeding 
animals  showing  severe  infestation  may  be  treated  by  trephining  the 
sinuses. 

Prevention. — To  prevent  the  fly  from  depositing  its  larvae  the  noses 
of  the  sheep  ma}^  be  smeared  with  tar.  For  the  convenient  application 
of  this  preventive  remedy  many  flock  owners  use  salt  logs  in  their  pas- 
tures. Into  these  logs  two-inch  holes  are  bored  at  intervals  of  about 
six  inches  in  each  of  which  a  little  "salt  is  kept  during  the  fly  season. 
Two  or  three  times  a  week  tar  is  smeared  with  a  brush  around  these 
holes  in  such  manner  as  to  smear  the  noses  of  the  sheep  as  they  en- 
deavor to  reach  the  salt.  The  logs  should  be  of  sufficient  length  to  enable 
all  the  sheep  to  get  to  them. 


CHAPTER  VII 
THE  FLEAS 

Order  II.  Siphonaptera. — Insecta  (p.  15).  Members  of  this  order 
have  the  body  compressed  laterally,  and  the  color  is  usually  dark  brown. 
The  head  is  small,  generally  bearing  a  single  ocellus  on  each  side,  com- 
pound eyes  are  absent.  The  mouth  parts  are  suctorial  but  differ  from 
those  of  the  order  Diptera  in  that  the  true  haustellum  is  lacking,  the 
sucking  structure  consisting  of  the  ventrally  grooved  labrum  and  the 
two  mandibles,  which  form  a  half-open  tube  (Fig.  36,  e  and  £).  The 
maxillae  are  sharp  and  serve  to  puncture  the  skin.  The  three  thoracic 
segments  are  distinct,  each  bearing  a  pair  of  well-developed  legs,  the 
posterior  pair  being  especially  long,  powerful,  and  adapted  for  leaping, 
which  is  the  principal  mode  of  progression. 

Metamorphosis  is  complete.  The  larvae  are  long,  slender,  without 
feet,  and  somewhat  hairy.  When  mature  the  larva  spins  a  cocoon  and 
enters  upon  a  distinct  pupal  stage.  During  this  stage  the  pupa  takes 
the  form  of  the  adult  with  the  appendages  enveloped  in  a  hard  pupal 
case.  At  no  stage  in  the  metamorphosis  are  there  traces  of  the  supposed 
ancestral  wings.  It  is  probable,  however,  that  the  fleas  have  descended 
from  winged  forms,  and  they  are  usually  considered  as  being  closely 
related  to  the  Diptera. 

There  are  many  species  of  fleas,  most  of  them  inhabiting  various  wild 
birds  and  mammals.  It  will  be  sufficient  here  to  consider  the  following 
three  of  the  family  Pulicidse : 

1.  Ctenocephahis  cam's,  the  dog  flea. 

2.  Ctenocephahis  felis,  the  cat  flea. 

3.  Pulex  irritans,  the  human  flea. 

The  two  species  of  Ctenocephahis  can  easily  be  distinguished  from 
Pulex  by  the  presence  in  the  former  of  comb-like  spines  on  the  lower 
margin  of  the  head  and  on  the  hinder  margin  of  the  prothorax.  These 
spines  are  dark  colored,  stout  and  closely  placed  (Figs.  34  and  35). 
The  dog  and  cat  flea  have  long  been  placed  together  under  the  one 
species  Pulex  serraticeps,  but  a  later  classification  recognizes  a  specific 
difference  based  principally  upon  the  form  of  the  head.  In  Ctenoceph- 
alus  cams  the  head,  when  seen  from  the  side,  is  rounded  in  front  and 
somewhat  less  than  t\vice  as  long  as  high.  The  head  of  C.  felis,  seen  from 
the  side,  is  more  acute  angled  in  front  and  is  long,  being  fully  twice  as 
long  as  high.    The  head  of  Pulex  irritans,  with  its  absence  of  spines,  is 


66 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


more  regularly  rounded  than  that  of  the  dog  flea,  and  bears  two  bristles, 
one  low,  in  the  vicinity  of  the  maxilla,  the  other  below  the  eye. 

Life  History.— In  their  life  history  the  fleas  undergo  a  complete 
metamorphosis.  The  eggs  are  oval,  0.5  mm.  in  length,  and  in  color 
pearly  white  (Fig.  36,  a).  They  are  deposited  loosely  and  unattached 
among  the  hairs  of  the  host,  dropping  off  readily  during  the  movements 
of  the  animal.  The  period  required  for  the  eggs  to  incubate  may  be 
from  one  to  four  days  or  longer,  depending  much  upon  temperature. 

The  larvae  are  white,  elongate,  apodal,  and  have  thirteen  segments, 
each  provided  with  bristles  (Fig.  37) .  They  are  very  active  and,  avoiding 
the  light  in  every  way  possible,  seek  such  shelter  as  is  afforded  by  crev- 


FiG.  34. — The  dog  flea,  anterior 
portion  of  body  (after  Osborn,  Bui. 
No.  5,  Bureau  of  Entomology, 
U.  S.  Dept.  of  Agr.). 


Fig.  35. — The  human  flea 
(Pulex  irritans),  anterior  por- 
tion of  body  (after  Osborn, 
Bui.  No.  5,  Bureau  of  Entomol- 
ogy, U.  S.  Dept.  of  Agr.). 


ices  in  the  floor,  carpets,  rubbish,  or  bedding  of  kennels,  such  material 
containing  fecal  or  other  organic  matter  upon  which  they  feed,  being 
especially  favorable  for  their  development. 

The  length  of  the  larval  stage  varies  considerably  under  the  influence 
of  temperature.  It  may  be  from  seven  to  thirty  days,  during  which 
time  there  are  two  molts.  Just  before  entering  the  pupal  stage  the 
larva  spins  a  white  silken  cocoon  within  which  the  pupa  (Fig.  36,  c)  is 
lodged  (Fig.  36,  b).  Transformation  to  the  fully  developed  imago — 
again  depending  upon  temperature  and  moisture — will  occupy  from 
five  to  ten  days.  The  time  required  for  the  development  of  the  mature 
insect  from  the  deposited  egg  is,  therefore,  from  thirteen  to  forty-four 
days,  with  twenty-eight  days  as  probal^ly  a  fair  average  under  our 
ordinary  climatic  conditions. 

Habits  and  Relation  to  Disease. — Nearly  all  species  of  fleas  have 
some  one  host  upon  which  they  prefer  to  live,  but  they  will  often  live 
and  thrive  upon  other  animals.     The  human  flea  will  infest  dogs  and 


THE  FLEAS 


67 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


cats  and  may  be  found  upon  these  animals  in  common  with  the  species 
usually  infesting  them.  As  a  pest  of  the  household  the  human  flea  is 
more  commonly  found  in  Europe  and  the  western  part  of  the  United 
States,  while  in  the  eastern  United  States  houses  may  be  rendered  un- 
inhabitable for  a  time  by  the  presence  of  the  dog  and  cat  flea. 

Fleas  are  of  importance  as  tormenting  parasites  of  man  and  domestic 
animals,  but  of  late  have  received  greater  attention  in  the  field  of  med- 
icine as  carriers  of  disease.  It  is  known  that  bubonic  plague,  which 
during  recent  years  has  made  its  appearance  on  the  Pacific  and  Gulf 
coasts  of  the  United  States,  is  transmitted  by  these  insects.  Tseniasis 
of  the  dog,  due  to  the  presence  of  Dipylidium  cani- 
num,  may  be  conve\^ed  to  humans  as  well  as  to  dogs 
through  the  intermediation  of  the  dog  flea,  while  a 
disease  of  infants  known  as  kala  azar,  occurring 
in  countries  bordering  on  the  Mediterranean,  is 
thought  to  be  transmitted  by  fleas. 

Usual  Hosts. — Our  larger  domestic  animals,  such 
as  horses,  cattle,  and  sheep,  are  rarely  attacked  b,y 
fleas.  Hogs  are  somewhat  less  free  from  them,  but, 
if  occurrmg  in  these  animals,  the  infestation  is  most 
always  light  and  causes  little  disturbance.  Dogs, 
cats,  rabbits,  fowls,  and  pigeons  are  especial  ob- 
jects of  attack.  Yomig  dogs  and  those  chamed 
up  are  more  likely  to  be  infested  as  they  live  amid 
conditions  favorable  to  the  breedmg  of  the  insects 
from  the  laying  of  the  eggs  to  their  full  develop- 
ment, which  is  particularl}-^  favored  by  litter  and 
wooden  floors.  Unlike  lice,  fleas  do  not  pass  their 
entire  cycle  upon  the  host,  nor  are  they  limited  to  a  particular  species. 
The  dog  and  cat  flea  will  readily  attack  man,  and  in  this  country  is  more 
troublesome  to  him  than  the  human  flea. 

Vitality. — When  feeding  upon  blood,  which  is  the  only  food  taken 
by  the  adults,  fleas  will  live  from  several  months  to  a  year.  Off  a  host 
the  dog  and  cat  flea  will  not  survive  longer  than  about  two  months,  the 
length  of  life  under  such  conditions  being  considerably  shortened  if  the 
w^eather  be  hot  and  dr}-. 

Treatment  and  Control. — Where  habitations  are  infested  by  these 
insects  it  is  of  first  importance  as  a  measure  of  control  that  dogs,  cats, 
and  other  domesticated  animals  kept  about  the  premises  receive  treat- 
ment that  will  rid  them  of  the  parasites.  The  harbormg  animals  maj' 
be  dusted  with  Persian  insect  powder  (pyrethrum),  the  remedy  being 
applied  liberally  and  driven  well  under  the  hair,  preferably  after  the 
skin  has  been  slightl.y  moistened.  This  will  not  kill  the  fleas  but  will 
stupify  them,  in  which  condition  they  will  drop  off  or  may  be  combed 


Fig.  37.— Pulex  irri- 
tans,  larva. 


THE  FLEAS  69 

from  the  hairs.  It  is  well  to  place  the  animal  while  undergoing  this 
treatment  upon  a  large  sheet  of  paper  which  may  later  be  rolled  up  and 
burned  with  the  collected  fleas.  In  severe  cases  creolin  or  lysol  solutions 
in  two  per  cent,  strength  may  be  used.  Quite  effectual,  but  more  expen- 
sive, is  the  preparation  consisting  of  Peruvian  balsam,  ten  parts;  creolin, 
two  parts;  alcohol,  one  hundred  parts  which  is  recommended  in  the 
treatment  for  lice  and  scab  mites  upon  small  animals.  In  the  treatment 
of  cats,  puppies,  and  chicks  the  powder  is  preferable  to  the  last  men- 
tioned preparations. 

Following  treatment  animals  should  not  ])e  permitted  to  re-enter 
their  sleeping  quarters  until  all  litter  has  been  removed  and  burned. 
In  order  that  this  cleanhig  up  process  may  be  effectual  every  detail 
must  be  looked  to.  Collections  of  dirt  and  dust  between  floor  boards 
must  be  removed,  as  well  as  every  particle  of  bedding  or  rubbish  that 
may  harbor  a  flea  brood.  After  this  preparation  the  quarters  should  be 
thoroughly  cleaned  with  hot,  soapy  water  and,  when  drj'^,  sprayed  with 
kerosene  or  kerosene  emulsion  (formulae,  page  48)  as  an  additional  pre- 
caution. For  kennels  a  bedding  should  be  used  which  can  be  frequently 
replaced,  as  shavings  or  straw.  Carpet  or  matting  should  never  be  used 
for  this  purpose. 

Household  Infestation. — In  dealing  with  household  infestation  it  is 
first  necessary  to  exclude  flea-bearing  animals  from  the  premises  or 
destroy  the  adults  which  are  producing  the  eggs  upon  these  hosts.  Flea 
larvse  find  excellent  conditions  for  development  under  tacked-down 
carpets  or  matting  and  in  spaces  between  floor  boards.  The  floor 
covering,  whatever  it  may  be,  should  be  removed,  beaten,  and  thor- 
oughly aired.  The  floors  may  then  be  swept  and  the  dust,  which  con- 
tains many  eggs  and  larvae,  collected  and  burned.  Kerosene  should 
then  be  applied  with  a  mop  in  such  manner  that  it  will  penetrate  all 
cracks  and  crevices  in  the  floor  and  beneath  the  baseboards.  Benzene 
is  often  advised  for  this  purpose,  but,  owing  to  the  extreme  danger  of 
ignition,  its  use,  excepting  under  the  most  careful  supervision,  is  not 
to  be  recommended. 

Following  these  eradicative  measures  the  floor  coverings  may  be  re- 
placed, but  before  doing  so  it  is  well,  as  an  additional  precaution,  to 
sprinkle  the  floors  Avith  pyrethrum  powder.  This  will  work  into  the 
fabric  and  make  the  carpet  or  matting  an  unfavorable  harbor  for  any 
larvai  or  adults  which  may  have  escaped  the  eradicative  measures. 
Where  the  floors  are  oiled  and  rugs  used  instead  of  carpets  or  matting, 
the  problem  of  getting  rid  and  keeping  rid  of  such  an  infestation  is  much 
lessened. 


CHAPTER  VIII 

THE   LICE 

There  has  been  much  disagreement  among  various  authors  as  to  the 
systematic  arrangement  of  the  hce.  The  classification  given  here,  if 
faulty,  will  perhaps  at  least  serve  the  purposes  of  this  work  until  exacting 
systematists  have  better  settled  the  matter. 

Order  III.  Siphunculata. — Insecta  (p.  15).  The  Sucking  Lice. — The 
lice  of  the  order  Siphunculata  have  the  suctorial  mouth  parts  at  the 
anterior  border  of  the  head,  the  movable  proboscis  being  formed  of  the 
upper  and  lower  lips  (Fig.  38).  Within  this  is  the  sucking-tube  which  is 
projected  beyond  its  sheath  and  buried  in  the  skin  when  used  to  aspirate 
blood.  The  eyes  are  two  simple  ocelli,  one  on  each  side.  The  antennae 
are  short.  The  thorax  is  usually  broader  but  shorter  than  the  head,  with 
indistinct  division  into  three  segments.  The  legs  are  short  and  thick,  the 
tarsi  terminatrng  in  a  single  claw.  There  are  no  wings.  The  abdomen 
is  large  and  generally  elliptical  in  outline.  The  last  abdominal  segment 
is  rounded  in  the  male  with  an  opening  for  the  penis.  Li  the  female 
this  segment  is  notched  and  has  two  small  terminal  appendages.  The 
female  is  from  L5  to  5  mm.  in  length,  the  male  somewhat  smaller. 

Life  History. — The  metamorphosis  is  incomplete.  The  young,  which 
leave  the  eggs  by  an  operculum,  have  the  shape  of  the  adults  but  do  not 
acquire  the  adult  color  and  consistency  until  after  several  molts. 

jhe  eggs  as  they  are  extruded  from  the  female  are  glued  fast  to  the 
hairs  of  the  host  by  means  of  a  viscid  secretion.  In  this  position  they 
are  commonh^  referred  to  as  nits,  which,  with  the  aid  of  a  hand  glass, 
will  be  observed  to  have  somewhat  the  shape  of  a  barrel  with  the  at- 
tached end  rounded  and  a  blunt  free  extremity  (Fig.  40,  e). 

Hatching  occurs  in  from  five  to  six  days,  the  young  in  general  re- 
sembling the  adults  excepting  in  size.  They  become  mature  in  about 
four  weeks. 

The  sucking  lice  come  into  one  family,  the  Pediculidse.  All  are  per- 
manent parasites,  the  entire  life  cycle  being  spent  upon  the  host.  All 
are  limited  to  a  specific  host,  and  will  only  accidentally  inhabit  a  host  of  a 
different  species.  Therefore  if  the  host  is  known,  the  specific  identity 
of  the  parasite  is  readily  determined. 

The  characteristics  of  the  species  are  here  given  under  their  respective 
host  animals.  It  may  be  said  of  the  sucking  lice  in  general  that  the  head 
is  inserted  directly  on  the  thorax,  their  antennae  are  five-segmented;  the 


THE  LICE  71 

segments  of  the  abdomen  numlier  eight  or  nine,  and  their  tarsi  are 
terminated  by  a  single  claw. 

Order  IV.  Mallophaga 

The  Biting  Lice. — Insecta  (p.  15).  The  members  of  the  order  of 
biting  lice  resemble  the  sucking  lice  in  general  form,  but  differ  from  them 
mainly  in  that  they  are  nuich  smaller  and  have  the  mouth  parts  adapted 
for  biting  and  mastication.  They  may  be  at  once  distinguished  by  the 
head  and  mouth  parts;  the  head  is  usually  rounded,  triangular,  squared, 
or  crescent-shaped,  and  is  broader  than  the  thorax  (Fig.  39).  Upon  the 
under  side  of  the  head  are  located  the  mandibulate  mouth  pieces  adapted 
for  cutting  and  feeding  upon  epidermic  scales,  hairs,  feathers,  and 
other  cutaneous  products.  The  eyes  are  simple  ocelli  located  back 
of  the  short  antennae  and  are  often  indistinct.  The  thorax  is  generally 
narrow,  the  prothorax  being  distinct,  the  two  posterior  segments  fused. 
The  legs  are  adapted  for  either  clasping  or  running;  in  the  first  case  the 
tarsi  terminate  in  a  single  claw  (Philopterida?),  in  the  second  the  tarsi 
are  long  and  terminate  in  two  claws  (Liotheidae).  Wings  are  absent. 
The  abdomen  is  generally  elliptical;  it  may  be  elongate,  or  short  and 
broad,  approaching  a  globular  outUne.  Their  relatively  small  size  and 
hard,  flattened  bodies  facilitate  their  movement  among  the  hairs  close 
to  the  body. 

In  their  breeding  habits  and  life  history  the  Mallophaga  agree  with 
the  preceding  order. 

Although  the  order  has  been  variously  subdivided,  it  will  be  sufficient 
here  to  place  the  biting  lice  according  to  their  hosts  in  the  two  families 
Philopteridse  and  Liotheidae,  the  former  including  the  biting  lice  of 
mammals  and  birds,  the  latter  the  lice  of  birds  only. 

Biting  lice,  like  the  suctorial,  are  limited  to  a  specific  host,  which  as  a 
uile  they  do  not  voluntarily  leave  unless  it  is  to  crawl  upon  another 
host  of  the  same  species,  in  which  case  the  migration  is  ordinarily  ac- 
complished when  the  bodies  of  the  host  animals  are  in  contact.  Lender 
conditions  of  severe  infestation  among  poultry  some  of  the  parasites 
may  pass  to  the  roosts  and  nests  and,  by  contact,  even  to  the  bod}'  of  a 
mannnalian  host,  but  they  will  not  survive  such  migrations  for  more  than 
a  few  hours. 

Pediculosis  of  Domestic  IMammals 

The  condition  commonly  known  as  lousiness  is  medically  referred  to 
as  pediculosis,  a  term  correctly  applied  whether  the  condition  be  due 
to  the  presence  of  either  the  sucking  or  the  biting  species.  The  term 
phthiriasis  should  properly  be  restricted  to  infestation  with  the  genus 
Phthirius  in  particular. 

Lousiness  is  usually-  accompanied  by  an  unthrifty  condition,  not 


72  PARASITES  OF  THE  DOMESTIC  ANIMALS 

necessarih'  resulting  from,  but  rather  predisposing  to  the  attack,  the 
reduction  in  the  functional  activity  of  the  skin  in  such  condition  afford- 
ing an  inviting  habitat  for  the  parasites.  Herbivorous  animals  which 
have  been  kept  for  a  prolonged  period  upon  dry  feed,  as  during  the 
winter  months,  are  those  most  likely  to  be  infested,  lice  rarely  being 
found  upon  these  animals  after  they  have  been  turned  upon  more 
succulent  food  and  the  winter  coat  has  been  shed. 

There  is,  in  fact,  little  valid  excuse  for  the  presence  of  these  parasites 
upon  our  domestic  animals  at  any  time.  Infestation  is  usually  the 
accompaniment  of  uncleanly,  impoverished,  and  crowded  conditions  of 
stabling  or  yarding.  Well  housed,  well  fed,  and  regularly  groomed 
animals  offer  no  attractions  to  lice,  and  animals  so  cared  for  will  not 
have  them.  Excepting  in  accidental  and  transient  incidents,  their  pres- 
ence upon  man  or  domesticated  beast  reflects  upon  man  in  either  case. 

Whether  the  degree  of  discomfort  and  injury  to  an  animal  due  to  the 
presence  of  lice  upon  its  l)ody  is  slight  or  serious  in  its  consequences  will 
depend  upon  the  number  present  and  the  group  to  which  thej^  belong. 
The  sucking  lice,  piercing  the  skin  and  feeding  upon  the  blood  and 
exudate,  cause  a  much  more  intense  pruritus  than  that  occasioned  by 
the  biting  lice  which,  in  their  habit  of  feeding  upon  surface  epidermic 
products  and  debris,  have  more  the  nature  of  scavengers. 

The  presence  of  the  lice,  as  well  as  their  location,  is  indicated  by  the 
pruritus,  by  their  eggs  or  nits  upon  the  hairs,  and  the  debris  of  their 
molts.  The  irritation  of  the  itching  and  rubbing,  together  with  the  loss 
of  blood  if  suctorial  lice  are  numerous,  results  in  emaciation  and  general 
unthriftiness  of  an  animal  likely  to  have  ])een  in  poor  condition  before 
becoming  infested. 

While  the  presence  of  lice  may  be  unmistakably  evident,  it  should 
be  made  quite  sure  that  there  is  not  also  present  a  form  of  acariasis. 
Lice  fi-equently  invade  animals  suffering  from  scabies,  and  the  pruritus, 
with  the  accompanying  scaly  and  scabby  condition  of  the  skin,  may  be 
due  to  scab  mites,  which,  minute  and  deeply  located,  may  be  readily 
overlooked.  The  presence  of  these  can  only  be  determined  with  cer- 
tainty by  examination  of  epidermic  scrapings  from  beneath  the  scabs. 
For  their  detection  and  examination  the  microscope  is  necessai;;y'.  They 
are,  however,  often  difficult  to  discover,  and  the  material  is  best  sub- 
mitted to  a  laboratory  for  examination  if  such  is  available.  More  de- 
tailed methods  of  diagnosis  and  treatment  of  this  condition  are  given 
elsewhere  under  the  discussion  of  the  scab  mites. 

Pediculosis  of  the  Horse 

Horses,  mules,  and  asses  harbor  one  species  of  sucking  louse,  Hcema- 
topinus  asini,  and  two  species  of  biting  lice,  Trichodectes  equi  and  T. 
pilosus. 


THE  LICE 


73 


38.  —  Hsematopinus 
asini  (after  Osborn,  from 
Comstock.  Bui.  No.^  5, 
Bureau  of  Entomology,  U. 
S.  Dept.  of  Agr.). 


1.  Haematopinus  asini  (H.  macrocephalus).— PediciilidiB  (p.  70). 
Head  long  and  narrow;  antenna  attached  at  lateral  protuberances  be- 
hind which  are  notches  lodging  the  eyes.  Anterior  to  this  the  head  is 
more  narrow  with  borders  parallel,  terminating 
in  a  blunt  point.  The  thorax  is  much  shorter 
than  the  head  and  widens  posteriority.  The 
abdomen  is  oval,  with  stigmata  placed  in  the 
middle  of  lateral  protuberances  on  the  margins 
of  segments.  The  general  color  is  yellow,  the 
thorax  brownish.  The  female  is  3  to  3.5  mm., 
the  male  2.5  mm.  in  length  (Fig.  38). 

2.  Trichodectes  equi  (T.  parumpilosus).  Phil- 
opteridie  (p.  71). — Head  slightly  longer  than 
broad  and  semicircular  in  front  of  the  antennae 
which  are  set  well  back.    The  abdomen  is  oval 

and  bears  eight  trans- 
verse dark  bands,  each 
upon  the  anterior  por- 
tion of  a  segment  and 
extending  from  the 
middle  line  about  half- 
way   to    the    margin. 

The  general  color  of  the  abdomen  is  yellowish, 
the  head,  thorax,  and  legs  chestnut  (Fig.  39). 
3.  Trichodectes  pilosus.  Philopteridae 
(p.  71). — Somewhat  smaller  than  the  preced- 
ing species.  Head  broader  than  long,  rounded 
in  front,  and  slightly  widened  at  the  temples. 
The  anteimse  are  inserted  well  forward,  almost 
on  a  line  with  the  head's  anterior  border,  in 
which  respect  it  markedly  differs  from  T.  equi. 
The  abdomen  tapers  posteriorly  and  has  upon 
the  middle  ofthe  first  seven  segments  darkened 
spots,  less  conspicuous  than  the  bands  simi- 
larly located  upon  T.  equi.  The  head,  thorax, 
legs,  and  abdomen  are  hairy  on  both  surfaces. 
The  general  color  is  yellow. 

Pediculosis  caused  b}-  suctorial  lice  upon  the 
horse  is  usuall}'  located  at  the  base  of  the  mane 
and  forelock,  and  at  the  root  of  the  tail.  The  hairs  about  these  parts 
are  likely  to  be  scant,  broken,  or  the  skin  entirely  denuded,  due  to 
the  rubbing  against  anything  within  reach.  During  the  act  of  rubbing 
the  animal  has  a  peculiar  habit  of  protruding  the  upper  lip,  or,  if  in 
reach  of  another  animal,  will  gently  bite  it. 


Fig.  39.  —  Trichodectes 
parumpilosus  (after  Osborn, 
Bui.  Xo.  5,  Bureau  of  Ento- 
mology, U.  S.  Dept.  of  Agr.). 


74 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Biting  lice  are  less  common  upon  horses  than  suctorial.  They  are  not 
often  found  on  the  upper  parts  of  the  body,  more  frequently  occupj'ing 
the  regions  of  the  neck,  breast,  and  between  the  fore  and  hind  legs. 
They  cause  less  pruritus  than  the  sucking  lice,  though  the  animals  will 
frequently  rub  bare  places  at  the  regions  infested.  Both  forms  may 
coexist  upon  the  same  animal. 

Pediculosis  of  the  Ox 

Two  species  of  suctorial  lice  inhabit  the  ox,  Hcematopinus  eurysternus, 
— the  short-nosed  ox  louse,  and  Linognathus  vituli, — the  long-nosed  ox 
louse.    Of  the  biting  species  there  is  but  one,  Trichodectes  scalaris. 

1.  Haematopinus  eurysternus.  Pediculidse  (p.  70). — Head  relatively 
short  and  broad,  rounded  in  front;  thorax  about  twice  as  wide  as  long, 


Fig.  40. — Haematopinus  eurysternus:  a,  female;  b,  rostrum;  c, 
ventral  surface  of  the  last  segments  of  male;  d,  same  of  female;  e,  egg; 
f,  surface  of  same  greatly  enlarged  (after  Osborn,  Bui.  No.  5,  Bureau 
of  Entomology,  U.  S.  Dept.  of  Agr.). 

widest  posteriorly.  The  abdomen  is  oval  and  much  larger  than  that  of 
the  sucking  louse  of  the  horse.  On  the  lateral  margin  of  each  abdominal 
segment  is  a  slightly  colored  tubercle.  In  the  female  two  black  blotches 
are  laterally  located  on  the  terminal  segment.  The  general  color  is 
yellowish  gray.  The  female  is  2  to  3  mm.,  the  male  2  mm.  in  length 
(Fig.  40). 

2.  Linognathus  vituli  (Haematopinus  vituli).  Pedicuhda?  (p.  70). — 
Somewhat  smaller  than  the  preceding.  The  head  is  long  and  narrow 
and  somewhat  sunken  in  the  thorax,  as  in  a  notch.  The  thorax  is  about 
as  broad  as  long.  The  abdomen,  like  the  head,  is  long  and  narrow, 
giving  to  the  entire  insect  a  long  and  slender  appearance.  The  general 
color  is  a  deep  chestnut.  The  female  is  2.5  to  3  mm.,  the  male  2  to  2.5 
mm.  in  length  (Fig.  41). 


THE  LICE 


75 


This  species  is  found  upon  calves,  though  it  will  also, — probably  as 
frequently, — infest  adults. 

3.  Trichodectes  scalaris.  Philopterida^  (p.  71). — Head  cone-shaped, 
rounded  at  the  temples  and  in  front,  about  as  broad  at  the  temples  as 
long.  The  antennoe  are  inserted  well  back 
and  are  usually  directed  backward.  The  al)- 
domen  is  not  so  tapering  as  in  the  ])iting  louse 
of  the  horse,  and  the  median  spots  are  larger, 
forming  bands  which  are  quite  distinct.  The 
general  color  is  white.  It  is  somewhat  smaller 
than  the  species  uifesting  the  horse  (Fig.  42). 
This  is  a  very  common  and  widely  dis- 
tributed species,  frequently  found  upon  cattle 
in  cohabitation  with  the  sucking  lice. 

Pediculosis  of 
the  ox,  caused 
by  either  the 
short  or  long- 
nosed  species, 
is  most  likely 
to  be  found 
about  the  ears, 

base  of  the  head,  and  along  the  dorsal 
line  of  the  neck,  back,  and  loins.  The 
intense  itching  causes  the  animal  to  rub 
against  any  convenient  object,  and  there 
is  frequent  licking  of  the  parts  which  can 
be  reached  with  the  lough  tongue.  As  a 
result  of  this  rubbing  large  patches  of 
skin  may  be  entirely  denuded  of  hair, 
and  the  skin  itself  in  severe  cases  may 
become  pustular  and  scabby. 

Contrary  to  what  has  been  observed 
in  the  horse,  biting  lice  probably  occur 
more  frequently  upon  the  ox  than  the 
sucking  species,  therefore  lousiness  of 
cattle  is  usually  accompanied  by  less 
itching.  As  to  their  location  the  l)iting  lice  of  cattle  do  not  limit  them- 
selves, usually  spreading  to  all  parts  of  the  body.  They  may  frequently 
be  observed  crawling  out  upon  the  hairs  and,  when  one  is  removed  and 
examined  with  a  hand  glass,  one  or  more  hairs  will  often  be  found  in  the 
clutch  of  its  claws. 


Fig.  41.  —  Hsematopinus 
vituli:  female,  under  surface 
of  last  segments  of  abdomen 
of  same  (after  Osborn,  Bui. 
No.  5,  Bureau  of  Entomol- 
ogy, U.  S.  Dopt.  of  Agr.). 


Fig.  42. — Trichodectes  scalaris 
(after  Osborn,  Bui.  No.  5,  Bureau 
of  Entomology,  U.  S.  Dept.  of 
Agr.). 


76 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Pediculosis  of  the  Sheep 

This  animal  has  one  suctorial  louse, — Litiognathus  pedalis,  and  one 
biting  louse, — Trichodedes  splicer ocephalus. 

1.  Linognathus  pedalis  (Hsematopinus  pedalis).  Pedicuhdae  (p.  70). 
— Has  the  same  general  shape  as  the  short-nosed  ox  louse,  but  is 
somewhat  more  slender.  It  is  also  much  lighter  in  color,  giving  it  a 
somewhat  immature  appearance  (Fig.  43). 


Fig.  43. — Hsematopinus  pedalis:  a,  adult  female;  b,  ventral  view  of  terminal  seg- 
ments of  same;  c,  terminal  segments  of  male;  d,  egg  (after  Osborn,  Bui.  No.  5,  Bu- 
reau of  Entomology,  U.  S.  Dept.  of  Agr.). 

This  species  is  rare.  It  is  said  to  occur  only  where  the  hair  is  short 
upon  the  legs  and  feet,  especially  about  the  dew-claws.  It  is  from  this 
location  that  it  gets  its  common  name,  "sheep-foot-louse." 

2.  Trichodectes  sphaerocephalus.  Philopterida  (p.  71). — Head 
broad  as  long,  giving  the  rounded  appearance  from  which  the  specific 
name  is  derived.  The  abdomen  is  elliptical,  each  segment  having  a 
median  band  which  is  somewhat  rounded  upon  its  anterior  border. 
The  general  color  is  white  (Fig.  44).    Of  rather  rare  occurrence. 

The  common  so-called  "louse"  of  sheep  is  not  a  true  louse,  but  the 
degenerate  fly  Melophagus  ovinus,  described  elsewhere  under  the  par- 


THE  LICE  77 

asites  of  the  order  Diptera.  Pediculosis,  properly  so  called,  is  seldom 
met  with  in  sheep.  While  the  sucking  lice  are  localized  to  the  lower 
parts  of  the  legs,  the  biting  lice  lie  deep  in  the  wool,  close  to  the  body, 
seriousl}'-  altering  the  fleece  by  cutting  the  fibers  with 
their  mandibles.  Their  location  makes  the  condition 
rather  a  difficult  one  to  contend  with. 

'Pediculosis  of  the  Goat 

Goats  have  one  suctorial  species, — Linognathus  steno])- 
sis.  The  biting  louse, — Trichodectes  climax,  is  fairly  com- 
mon and  is  the  only  species  of  this  genus  upon  goats  that 
is  well  established.  _Tn- 

1.  Linognathus  stenopsis  (Hsematopinus  stenopsis).  ehodeotes  spha?- 
Pediculidae  (p.  70). — Head  long,  narrow,  and  rounded  in  rocephaius  (af- 
front; there  are  two  lateral  notches,  below  which  are  tf  ^f  °r„S!!I: 
widened  temples,  r  rom  these  the  head  narrows  rapidl}'  of  Entomology, 
and  becomes  deeply  fitted  into  the  thorax.  The  thorax  U.  s.  Dcpt.  of 
is  widest  posteriorly  where  it  is  somewhat  concaved  upon      ^^''' 

the  abdomen.  The  abdomen  in  outline  is  an  elongated  oval  with  stig- 
mata near  lateral  margins  of  segments.  The  female  is  2  mm.;  the  male 
1.5  mm.  in  length. 

2.  Trichodectes  climax.  Philopteridse  (p.  71). — Head  quadrangular 
in  shape  and  broader  than  long.  The  abdomen  is  oval  with  median 
dark  bands  upon  the  segments.  The  head  and  thorax  are  reddish 
brown ;  the  abdomen  is  pale  yellow. 

During  the  winter  months  especially',  goats  are  apt  to  harbor  lice  in 
rather  large  numbers.  As  in  other  animals  the  sucking  louse  produces 
the  greater  irritation.  The  skin  ma}'^  become  bare  in  places  with  numer- 
ous inflamed  and  ulcerated  areas  covered  with  crusts.  In  Angora  goats 
especially,  the  biting  louse  causes  a  great  depreciation  from  its  habit  of 
cutting  the  hairs  with  its  mandibles. 

Pediculosis  of  the  Hog 

Domesticated  and  wild  hogs  have  one  species  of  louse,  Hcematopinus 
suis  (H.  urius).  This  is  the  largest  known  member  of  the  suctorial 
group.  The  head  is  very  long  and  narrow,  cone-shaped,  and  rounded 
in  front;  just  posterior  to  the  attachments  of  the  antennae  are  horn-like 
protuberances,  forming  deep  notches.  The  thorax  is  somewhat  broader 
than  long;  dark,  transverse  bands  may  be  noted  upon  the  legs.  The 
abdomen  is  oval  in  outline,  with  distinct  segment  borders;  the  stigmata 
are  upon  prominent  lateral  protuberances.  The  thorax  is  brownish 
red  in  color;  the  head  and  abdomen  yellowish  gray.  The  female  is  5 
mm.;  the  male  4  mm.  in  length  (Fig.  45). 

This  louse  is  a  very  active  blood  sucker,  living  upon  hogs  of  any  age 


78 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


or  condition  and  everywhere  where  these  animals  are  found.  The 
intensity  of  the  pruritus  produced  is  proportionate  to  the  parasite's 
size,  the  skin,  as  they  increase  in  nuniberS;  becoming  covered  with 
papules  and  scales.     The  constant  itching  and  worry,  which. seems  to 

be  most  severe  at  night,  is  evidenced 
by  the  restlessness  of  the  animals 
and  their  violent  scratching  against 
any  available  object.  Such  a  con- 
dition seriously  interferes  with  the 
growth  and  fattening  of  hogs,  and 
young  pigs  especially  will  often 
succumb  to  loss  of  blood  and  ex- 
tensive irritation  and  excoriation 
of  the  skin. 

Pediculosis  of  the  Dog 

Dogs  have  one  sucking  louse, 
Linognathus  piliferus  and  one  biting 
louse,  Trichodectes  latus. 

1.  Linognathus  piliferus  (Haema- 
topinus  piliferus).  Pediculidae 
(p.  70). — Head  thick,  about  as  wide 
as  long,  rounded 
in  front.  The 
thorax  anteri- 
orly is  but  slightly  wider  than  the  head;  abdomen 

elongate  oval  in  outline,  the  margins  of  the  segments 

appearing  somewhat  rounded ;  stigmata  marginal  and 

distinct.    The  general  color  is  yellowish  white.    The 

female  is  2  mm. ;  the  male  L5  mm.  in  length  (Fig.  46). 
2.  Trichodectes    latus.    Philopteridae   (p.  71). — 

Entire  insect  broad  and  short;  more  than   half  as 

broad  as  long.    The  head  large,  slightly  rounded  in 

front,  and  broader  than  long.    The  abdomen  of  the 

female  is  broad  and  somewhat  globular  in  outline. 

The  median  abdominal  bands  or  spots  are  absent. 

The  general  color  is  bright  yellow  (Fig.  47). 

Dogs  do  not  seem  to  be  as  seriously  affected  as  Bureau  of  Entomoi- 

other  animals  by  the  presence  of  lice.     The  sucking  °^^'  ^-  ^-  ^^p*'  °^ 

louse  is  the  more  tormenting,  and  is  usually  found 

about  the  chin,  under  part  of  the  neck,  and  breast,  though,  with  the 

biting  louse,  it  may  be  found  on  any  part  of  the  body.     The  biting 

species  is  most  often  found  upon  puppies. 

The  biting  louse  infesting  dogs  is  particularly  of  medical  interest  in 


Fig.  45.  —  Haematopinus  suis  (from 
jDhotograph  of  mounted  specimen,  bv 
Hoedt). 


Fig.  46. — Haemato- 
pinus piliferus  (after 
Osborn,  Bui.    No.   5, 


THE  LICE 


79 


being  a  larval  host  of  the  common  tapeworm  of  the  dog,  Dipylidium 
cajiinum,  as  is  also  the  dog  flea,  Ctenoceyhalus  canis.  Infection  of  the 
louse  by  the  larva  {Cysticercus  trichodedes)  is  readily  brought  about 
through  ingestion  of  the  eggs  of  the  tapeworm  which  may  have  col- 
lected about  the  anus  or  in  the  litter  of  the  kennel. 
This  tapeworm  is  occasionally  found  to  be  present  in 
the  intestines  of  human  beings,  particularly  children. 
It  is  quite  conceivable  how  such  infestation  might 
occur  in  the  fondling  of  lousy  or  flea-infested  dogs, 
especially  if  the  person's  food  be  about  at  the  same 
time  to  act  as  a  vehicle  for  the  insects  containing  the 
larva. 

Pediculosis  of  the  Cat 

Trichodectes  subrostratus,  the  only  louse  harbored  Fig.  47.  —  Tri- 
by  the  cat,  is  about  the  same  length  as  the  biting  louse  ^'\°^f°^t1-  ^^^^^ 
of  the  dog  (1  to  1.3  mm.),  but  is  not  so 
broad,  and  is  distinguished  by  its  pointed 
head,  which  is  slightly  longer  than  broad. 
The  abdomen  is  oval,  with  median  bands. 
The  head  and  thorax  are  bright  yellow  in  color,  the  abdo- 
men whitish  (Fig.  48). 

Lousiness  is  not  often  met  with  in  the  cat;  when  it  does 
occur  it  is  usually  the  accompaniment  to  a  debilitated 
condition  in  young  animals. 


(after  Osborn,  from 
Denny,  Bui.  No.  5, 
Bureau  of  Ento- 
mology, U.  S.  Dept. 
of  Agr.). 


Fig.  48.— 
Trichodectes 
subrostratus 
(after  Os- 
born, Bui. 
No.  5,  Bu- 
reau of  En- 
tomology, 
U.  S.  Dept. 
of  Agr.). 


Pediculosis  of  Man 

Three  species  of  pediculi  infest  man,  Pediculus  humanus 
{P.  capitis),  the  head  louse,  P.  corporis  (P.  vestimenti),  the 
body  louse,  and  Phtkirius  pubis  (P.  inguinalis)  the  pubic 
or  so-called  "crab-louse." 

1.  Pediculus  humanis.  Pedicuhdae  (p.  70). — The  head 
is  somewhat  diamond-shaped,  short,  and  about  as  broad 
as  long.     The  abdomen  has  seven  distinct  segments,  each 

bearing  stigmata  laterally  placed.    Color  gray  with  darkened  margins. 

The  color  is  said  to  vary  from  light  to  dark  according  to  the  color  of 

the  skin  or  hair  of  the  host.    The  female  is  2.5  to  3  mm. ;  the  male  about 

2mm.  in  length. 

2.  Pediculus  corporis.  Pedicuhdae  (p.  70). — Resembles  preceding 
species,  of  which  it  is  regarded  by  some  authorities  as  merely  a  variety. 
It  is  slightly  larger.  The  color  is  grayish-white.  It  lives  upon  the 
clothing  of  its  host,  crawhng  upon  the  body  to  feed. 

3.  Phthirius  pubis.  Pediculidae  (p.  70). — Distinctly  differs  in  ap- 
pearance from  the  two  preceding.    The  head  is  short  and  thick,  fitting 


80  PARASITES  OF  THE  DOMESTIC  ANIMALS 

into  a  broad  concavity  in  the  thorax.  The  thorax  is  broad  and  appar- 
ently fused  with  the  abdomen,  the  two  forming  a  somewhat  heart- 
shaped  body  with  base  anterior.  The  first  pair  of  legs  is  much  more 
slender  than  the  second  and  third  which  are  stout  and  terminated  by 
powerful  claws  fitted  for  clasping  the  hairs.  The  female  measures  about 
1.5  mm.;  the  male  about  1  mm.  in  length.  It  infests  the  hairs  of  the 
pubic  region  and  of  the  armpits,  rarely  passing  to  other  parts. 

Of  these  three  species  Pediculus  humanus  is  the  most  widely  dis- 
tributed. 

Pediculosis,  Control  and  Treatment 

Contagion  in  pediculosis  is  due  to  the  rapid  succession  of  generations 
of  lice,  their  passage  from  host  to  host  being  facilitated  by  close  associa- 
tion, grooming  utensils,  blankets,  harness,  bedding,  etc.  It  is  possible 
for  domestic  animals  of  different  species  to  infect  each  other.  Such 
migrations,  however,  are  usually  of  an  accidental  nature,  and  the 
parasites  will  not  as  a  rule  remain  to  multiply  upon  a  host  foreign  to 
them. 

Long  hair,  especially  if  combined  with  unclean  conditions,  predis- 
poses to  lousiness.  If  in  addition  there  is  debihty,  the  etiologic  factors 
become  ideal.  Plenty  of  nutritive  food  and  a  thorough  cleaning  up  of 
animals  and  their  surroundings  are,  therefore,  essential  to  success,  what- 
ever measures  of  eradication  may  be  appHed. 

After  the  removal  and  burning  of  litter  the  stables,  kennels,  etc.,  may 
be  treated  with  boiling  water  and  afterward  whitewashed  or  washed  with 
a  three  to  five  per  cent,  creolin  solution.  For  spraying  interiors  an 
emulsion  of  kerosene  (formuhie,  page  48),  or  the  lime-sulphur  prepara- 
tion (page  125)  may  be  used. 

Clipping  of  long-haired  animals,  which  may  include  the  horse  and 
ox,  greatly  simplifies  their  treatment.  The  Melophagus  infesting  sheep 
is  removed  with  the  fleece  at  time  of  shearing,  the  anunal  soon  ridding 
itself  of  any  which  may  have  remained  upon  the  skin. 

Among  the  considerable  number  of  insecticide  agents  used  upon  the 
bodies  of  infested  animals  but  one  or  two  of  those  most  effectual  and 
most  commonl}^  emploj^ed  need  be  mentioned  here.  A  decoction  of 
tobacco,  one  ounce  to  the  quart  of  water,  as  a  local  application  answers 
well  for  all  animals.  In  using  this  preparation  the  possibihty  of  nicotine 
poisoning  should  be  kept  in  mind.  Large  areas  of  the  body  should  not 
be  dressed  at  the  same  time. 

Horses  may  be  treated  with  creolin  two  to  three  per  cent.,  or  kerosene 
emulsion.  Brushes  and  combs,  after  having  been  disinfected  by  scald- 
ing, may  have  a  Httle  kerosene  sprinkled  upon  them  as  thej^  are  used. 
Preparations  of  kerosene  should  not  be  applied  to  sweating  animals  or 
while  they  are  exposed  to  hot  sunshine.    Friction  with  fatty  substances, 


THE  LICE  81 

as  linseed  oil,  will  kill  by  asphyxia  lice  with  which  it  comes  in  contact. 
This  treatment  is  more  effectual  if  kerosene  be  shaken  up  with  the  oil 
in  the  proportion  of  one  of  the  former  to  two  of  the  latter.  A  mixture  of 
kerosene,  sulphur,  and  lard,  equal  parts,  is  also  quite  useful  for  this  pur- 
pose. 

These  treatments  will  apply  to  cattle  as  well  as  to  horses.  Where 
large  numbers  of  cattle  are  affected  resort  must  be  had  to  spraying  with 
kerosene  emulsion  or  dipping.  For  the  latter  purpose  ordinary  sheep 
dip  or  a  lime-and-sulphur  preparation  may  be  used. 

The  large  sucking  louse  of  the  hog  is  found  principally  inside,  behind, 
and  in  front  of  the  ears,  on  the  breast,  and  on  the  inner  side  of  the  el- 
bows. For  this  animal  the  stronger  preparations  of  the  insecticides 
should  be  used,  as  creolin  five  per  cent,  or  kerosene  and  oil  equal  parts. 
The  kerosene,  sulphur,  and  lard  mixture  is  quite  a  suitable  one  for  these 
animals.  It  is  well  also  to  treat  their  wallows  with  a  three  to  five  per 
cent,  solution  of  creolin. 

For  dogs  creolin  in  two  per  cent,  strength  is  quite  satisfactory.  Long- 
haired dogs,  especially  if  heavily  infested,  should  be  clipped  before 
treatment.  For  small  house  animals,  as  toj^  dogs  and  cats,  pyrethrum 
powder,  apphed  to  the  moistened  skin  as  for  fleas,  is  most  suitable. 

Whatever  insecticide  is  used  it  is  well  to  apply  vinegar  in  conjunction 
with  it.  This  may  be  added  to  the  fluid  preparations  in  the  proportion  of 
about  ten  ounces  to  the  quart,  or  it  may  be  applied  separately  diluted 
with  twice  its  quantity  of  water.  The  vinegar  has  a  destructive  action 
upon  the  eggs  which  may  survive  the  ordinary  remedies  used  to  destroy 
the  insects. 

Sodium  fluoride,  which  is  recommended  in  the  treatment  of  lice  of 
poultry,  all  of  which  are  biting  lice,  should  also  be  effective  for  the  biting 
lice  of  mammals,  though  experience  with  it  up  to  the  present  time  is  not 
sufficient  to  have  established  its  value  in  such  cases.  In  its  application 
it  should  be  rubl)ed  into  the  hair  over  all  parts  of  the  body.  The  treat- 
ment is  only  applicaljle  to  biting  lice. 

All  measures  used  for  the  eradication  of  lice,  whether  in  the  quarters 
or  upon  the  bodies  of  their  hosts,  should  be  repeated  at  least  three  times 
at  intervals  of  eight  to  ten  days.  This  is  necessary  to  destroy  the  hce 
which  may  emerge  from  remaining  eggs. 


CHAPTER  IX 

LICE   OF  POULTRY.     THE  BEDBUG 

Birds  under  the  usual  conditions  of  domestication  are  especially- 
prone  to  lousiness;  there  are,  in  fact,  few  fowls  entirely  free  from  them. 
Though,  relative  to  their  numbers,  lice  upon  poultry  probably  do  less 
harm  than  the  blood-sucking  ticks,  their  rapid  multiplication,  and  the 
fact  that  they  pass  their  entire  cycle  upon  the  bodies  of  their  hosts, 
make  it  probable  that  any  degree  of  infestation  will  become  a  destruc- 
tive nuisance.  The  constant  annoyance  due  to  their  crawling  upon 
the  skin  and  among  the  feathers,  with  the  energy  expended  in  the  efforts 
to  be  rid  of  them,  causes  fowl  to  droop  and  become  ready  victims  to  other 
diseases  commonly  affecting  poultry.  Flesh  and  egg  production,  under 
such  conditions,  must  essentially  be  retarded  to  a  degree  commensurate 
to  the  infestation. 

Young  chicks  are  especially  apt  to  succumb.  The}^  give  evidence  of 
the  presence  of  lice  by  drowsiness,  refusal  to  eat,  and  an  emaciated 
body.  The  symptoms  are  generally  accompanied  by  a  loss  of  feathers, 
especially  about  the  head  and  lower  part  of  the  neck.  Chickens  hatched 
in  an  incubator  should  be  free  from  them,  and  they  will  remain  so  unless 
placed  with  a  lousy  hen  or  put  in  infested  quarters. 

The  head  and  upper  part  of  the  neck  afford  a  protective  location  for 
the  lice,  as  they  cannot  here  be  reached  by  the  beak.  They  may,  how- 
ever, especially  in  older  birds,  be  found  upon  all  parts  of  the  body. 

The  biting  species  with  which  birds  are  infested  belong  with  either  the 
Philopteridse  or  Liotheidse,  the  former  containing  species  harbored  by 
both  mammals  and  birds,  the  latter  lice  of  birds  only. 

Lice  of  Chickens 

The  Philopteridse  of  chickens  are  Goniocotes  gallince,  G.  gigas,  Lipeurus 
caponis,  and  L.  heterographus. 

\.  Goniocotes  gallince  {G.  hologaster). — Head  broad  as  long;  anterior 
border  rounded;  angular  at  temples.  Abdomen  sac-like  in  outline,  hav- 
ing curved  bands  upon  lateral  l^orders  of  segments;  transverse  patches 
in  double  row.  General  color  dirty  yellow.  Female  about  1  mm.  in 
length. 

A  common  species. 

2.  Goniocotes  gigas  (G.  abdominalis) . — Head  rounded,  circular  in 
front.     Thorax  narrow.     Abdomen  large  and  but  slightly  longer  than 


LICE  OF  POULTRY.     THE  BEDBUG 


83 


broad;  each  segment  marked  laterally  by  long  tongue-shaped  spots. 
The  general  color  is  yellowish.  The  female  is  3  to  3.5  mm.  in  length,  a 
size  exceptional  in  this  genus  (Fig.  49). 

About  as  common  as  the  preceding  species. 

3.  Lipeurus  caponis  (L.  variabilis). — In  all  members  of  this  genus  the 
body  is  elongated  and  narrow.  Head  longer  than  broad  and  rounded  in 
front.  Abdomen  long  and  slender  with  black  margins.  Color  yellowish 
white.    Female  about  2  mm.  in  length  (Fig.  50). 

By  its  long  and  slender  appearance  this  species  can  easily  be  dis- 
tinguished from  others  mfesting  the  chicken.    It  is  not  very  common. 

4,  Lipeurus  heterographus. — Head  more  narrow  in  front  and  body 
much  stouter  than  in  preceding  species.     Abdomen  elongated  oval  in 


Fig.  49. — Gonio- 
cotes  abdominalis 
(after  Osborn,  from 
Denny,  Bui.  No.  5, 
Bureau  of  Entomol- 
ogy, U.  S.  Dept.  of 
Agr.). 


Fig.  50. — Lipeu- 
rus variabilis  (after 
Osborn,  from 
Denny,  Bui.  No.  .5, 
Bureau  of  Entomol- 
ogy, U.  S.  Dept.  of 
Agr.). 


Fig.  51. — Menopon 
pallidum  (after  Os- 
born, from  Denny, 
Bui.  No.  5,  Bureau 
of  Entomology,  U. 
S.  Dept.  of  Agr.). 


outline  with  median  spots  on  each  ring.  General  color  pale  yellow. 
Female  2  nun.  in  length. 

This  species  has  not  been  often  observed  in  this  country.  It  is  said 
to  also  occur  upon  certain  species  of  pheasants. 

Of  the  Liotheidffi  chickens  are  hosts  to  two  species,  Menopum  trig- 
onocephalum  and  M.  biseriaium. 

5.  Menopum  trigonocephalum  (M.  pallidum;  Menopon  pallidum). — 
Head  somewhat  triangular,  rounded  in  front  and  at  the  temples.  Abdo- 
men of  female  elongated  oval  in  outline,  in  male  longer  and  narrower. 
Legs  stout  and  hairy.  Color  light  yellow.  Female  about  1.5  mm.  in 
length  (Fig.  51). 

This  is  the  most  prevalent  of  all  of  the  hen  lice.  It  is  an  active  runner 
and  passes  readily  to  other  species  of  birds. 

6.  Menopum  biseriatum  (Menopon  biseriatum). — Head  somewhat 
crescent-shaped.    Legs  stout.    Abdomen  elongate.    Has  the  same  gen- 


84  PARASITES  OF  THE  DOMESTIC  ANIMALS 

eral  color  as  M.  trigonocephalum,  but  is  larger.    Female  about  2.5  mm.  in 
length  (Fig.  54). 

Less  common  than  preceding  species.  It  attacks  young  chicks,  espe- 
cially about  the  head  and  anus.  It  may  also  be  found  upon  turkeys  and 
peafowl. 

Lice  of  Turkeys 

The  Philopteridse  of  turkeys  are  Goniodes  stylifer  and  Lipeurus 
meleagridis. 

1.  Goniodes  stylifer. — Head  broad  as  long,  well  rounded  in  front,  with 
posterior  angles  projected  backward  into  pomts  which  are  terminated  bj^ 
strong  bristles.  Thorax  angular  and  narrowed  anteriorly.  Legs  slender 
and  hairy.  Abdomen  broad,  with  tongue-shaped  bands  on  the  sides. 
Hairs  are  numerous  and  long  on  both  surfaces.  Color  yellowish  white. 
Female  about  3  mm.  in  length  (Fig.  52). 

This  is  a  large  species  common  upon  turkeys  everywhere. 

2.  Lipeurus  meleagridis  (L.  polytrapezius) . — Head  longer  than  broad, 
romided  in  front  and  at  the  temples.  Thorax  and  abdomen  narrow  and 
elongate;  last  abdominal  segment  in  female  deeply  notched.  Color  pale 
yellow.    Female  about  2.8  mm.  in  length  (Fig.  53). 

Also  quite  common. 

The  Menopum  of  the  turkey  is  M.  hiseriatum  (Fig.  54),  referred  to 
under  the  Liotheidae  of  chickens. 

Lice  of  Ducks  and  Geese 

Of  the  Philopteridse  ducks  and  geese  harbor  two  species,  Philopterus 
icterodes  and  Lipeurus  anatis. 

1.  Philopterus  icterodes  {Docophorus  icterodes). — Head  longer  than 
broad,  rounded  m  front;  lower  portion  expanded  and  rounded.  Abdo- 
men oval  in  outline,  white  in  center,  and  with  dark  lateral  bands.  Color 
brownish  red.    Female  1  mm.  in  length. 

Of  common  occurrence. 

2.  Lipeurus  anatis  (L.  squalidus). — Head  longer  than  broad,  cone- 
shaped,  rounded  in  front.  Thorax  and  abdomen  elongate  with  dark 
borders.  On  the  abdomen  the  border  is  broken  into  patches  correspond- 
ing with  the  segments.  General  color  light  yellow.  Female  about  4  mm. 
in  length  (Fig.  55). 

Frequently  found  upon  both  domestic  and  wild  ducks. 
The  Liotheidae  of  ducks  and  geese  are  Trinotwn  luridum  and  T. 
lituratum. 

3.  Trinotwn  luridum  (Trinoton  luridum). — Head  as  wide  as  long, 
somewhat  triangular  m  shape,  with  rounded  corners.  Thorax  longer 
than  head.     Abdomen  long  and  narrow,  with  dark  bands  upon  the 


LICE  OF  POULTRY.     THE  BEDBUG 


85 


Fig.  52. — Goniodes  stylifer 
(after  Osborn,  Bui.  No.  5,  Bu- 
reau of  Entomology,  U.  ^S 
Dept.  of  Agr.). 


Fig.  53. — Lipeurus  polytrapezius 
(after  Osborn,  from  Piaget,  Bui.  No.  5, 
Bureau  of  Entomologv,  U.  S.  Dept  .'of 
Agr.). 


Fig.  54. — Menopon  biseriatum  (after 
Osborn,  Bui.  No.  5,  Bureau  of  Entomol- 
ogy, U.  S.  Dept.  of  Agr.). 


Fig.  55. — Lipeu- 
rus squalidus  (after 
Osborn,  Bui.  No.  5, 
Bureau  of  Entomol- 
ogy, U.  S.  Dept.  of 
Agr.). 


86  PARASITES  OF  THE  DOMESTIC  ANIISIALS 

segments.  Entire  insect  long  and  narrow.  General  color  grayish. 
Female  4  mm.  in  length  (Fig.  56). 

A  common  species. 

4.  Trinotum  lituratum  (Trinoton  lituratum). — Shorter  and  smaller 
than  the  preceding  species,  with  head,  thorax,  and  abdomen  relatively 
broader.  Legs  broad  and  stout.  Abdommal  segments  bordered  by 
darkened  spots.    Color  white. 

This  species  occurs  upon  domestic  geese. 

Lice  of  Swan 

Philopterus  cygni  and  Ornitlionomus  cygni  are  species  of  Philopteridse 
harbored  by  swan. 

1.  Philopterus  cygni  (Docophorus  cygni). — Head  about  as  broad  as 
long,  rounded  in  front.  Thorax  short  and  narrow.  Abdomen  sacular, 
white  in  center,  darkened  at  sides.  Head,  thorax,  and  legs  reddish 
brown.    Female  1  mm.  in  length  (Fig.  57). 

This  is  the  "Little  Red  Swan  Louse."    It  is  quite  common. 

2.  Ornithonomus  cygni  {Ornithobiiis  bucephalus;  0.  cygni). — Head 
massive  and  nearly  as  broad  as  long.  Thorax  about  the  same  length  as 
head.  Abdomen  narrow  oval,  tapering  toward  apex;  black  points  on 
outer  margins  of  four  of  the  abdominal  segments.  The  bodj'  is  trans- 
parent and  much  flattened.  General  color  white.  Female  4  mm.  in 
length  (Fig.  58). 

Occurs  in  great  abundance  on  all  species  of  swan. 

Lice  of  Pigeons 

The  more  common  Philopteridse  of  pigeons  are  Goniocotes  compar, 
Goniodes  damicornis,  and  Lipewus  columbce. 

1.  Goniocotes  compar. — Head  large,  nearlj'  as  broad  as  long,  rounded 
in  front.  Thorax  narrow.  Abdomen  broad  oval.  Color  dirty  yellow. 
Female  about  1.3  mm.  in  length  (Fig.  59). 

Found  quite  frequenth'. 

2.  Goniodes  damicornis. — Head  about  as  broad  as  long,  rounded  in 
front,  angular  behind.  Legs  stout.  Abdomen  broad  and  short.  Color 
t)rown.    Female  2  mm.  in  length  (Fig.  60). 

Not  as  common  as  preceding  species. 

3.  Lipeurus  columbce  (L.  baculus). — Characterized  by  its  extreme 
slenderness.  Head  long  and  narrow,  as  is  also  the  thorax  and  abdomen. 
Upon  the  abdominal  segments  are  brownish  patches.  Head  and  thorax 
brownish  red  in  color;  abdomen  dusky.    The  female  is  2  mm.  in  length. 

Occurs  abundantlv. 


LICE  OF  POULTRY.     THE  BEDBUG 


Fig.  56.— Trino- 
ton  luridum  (after 
Osborn,  Bui.  No.  5, 
Bureau  of  Entomol- 
ogy, U.  S.  Dept.  of 
Agr.). 


Fig.  57. — Docophorus 
cygni  (after  Osborn,  Bui. 
No.  5,  Bureau  of  Ento- 
mology, U.  S.  Dept.  of 
Agr.). 


M 

w 

Fig.  5)S.  —  Ornithobius  cygni 
(after  Osborn,  Bui.  No.  5,  Bureau 
of  Entomology,  U.  S.  Dept.  of 
Agr.). 


^^try^ 

,M 

3    ' 

1 

T~~- — ^— 

Fig.  59. — Goniocotes  corn- 
par  (after  Osborn,  Bui.  No.  5, 
Bureau  of  Entomology,  U.  S. 
Dept.  of  Agr.). 


Fig.  60. — Goniodes  dani- 
icornis  (after  Osborn,  Bui. 
No.  5,  Bureau  of  Entomol- 
ogy, U.  S.  Dept.  of  Agr.). 


88  PARASITES  OFfcTHE  DOMESTIC  ANIMALS 

CONTROL^AND    TREATMENT 

In  dealing  with  lice  of  poultry  we  should  first  discriminate  between 
the  lice  and  the  ticks,  bearing  in  mind  that  the  latter  do  not  breed  upon 
their  hosts.  According  to  whether  they  be  one  or  the  other  the  treatment 
will  be  modified  somewhat,  though  certain  measures  of  eradication  may 
be  suitable  for  either.  All  species  of  lice,  without  a  known  exception, 
passing  their  transformation  upon  the  host,  there  may  be  confidence  in 
attacking  them  that  there  are  no  eggs  and  young  developing  in  some 
out-of-the-way  retreat,  as  in  the  case  of  ticks  or  bedbugs. 

As  a  means  of  controlling  bird  lice  the  dust  bath  should  receive  first 
attention.  The  fine  dust  particles  enter  the  spiracles  of  the  insects, 
killing  them  by  suffocation,  therefore,  of  whatever  material  it  may  con- 
sist, the  dust  will  be  most  effectual  when  fine  and  penetrating.  Road 
dust  is  usually  quite  suitable;  it  will  be  the  more  efficient  if  powdered 
tobacco  be  added  in  the  proportion  of  about  one  of  tobacco  to  five  of 
dust.  Fine  ashes,  in  which  powdered  sulphur  is  mixed,  make  an  ex- 
cellent dust  wallow.  A  mixture  of  road  and  lime  dust,  with  the  addition 
of  a  cupful  or  two  of  sulphur,  may  be  used  with  as  good  results.  The 
dust  baths  should  be  in  deep  and  roomy  boxes  placed  where  they  will  be 
sheltered  from  the  rain. 

As  an  insecticide  for  the  individual  treatment  of  badly  infested  birds, 
any  oleaginous  substance  is  effectual.  As  with  dust,  the  principle  upon 
which  its  use  is  based  is  that  of  suffocation,  the  unctuous  agent  serving 
to  plug  the  breathing  pores  of  the  insect.  A  mixture  of  lard  and  sulphur 
answers  well  for  all  birds.  It  should  especially  be  applied  at  the  throat, 
upper  neck,  bases  of  the  wings,  and  at  the  base  of  the  tail  feathers.  If  a 
powder  is  used,  as  pyrethrum,  the  skin  should  be  first  moistened  with 
soapy  water  or  equal  parts  of  glycerin  and  water  and  the  powder  then 
blown  well  under  and  through  the  feathers. 

Investigations  by  the  United  States  Bureau  of  Entomology  with 
sodium  fluoride  have  demonstrated  that  lice  infesting  poultry  may  be 
readily  destroj-ed  by  the  application  of  a  small  quantity  of  this  powder. 
It  may  be  used  in  the  powdered  form  or  as  a  dip.  Applied  by  the  former 
method,  it  should  be  sprinkled  under  the  feathers  of  the  neck,  breast, 
back,  tail,  below  the  vent,  and  upon  the  under  side  of  each  wing  as  these 
are  spread.  If  used  as  a  dip,  this  may  be  prepared  by  adding  one  ounce 
of  commercial  sodium  fluoride  to  the  gallon  of  water.  The  solution 
should  be  made  tepid  and  the  entire  body  of  the  fowl,  excepting  the 
head,  immersed  in  it.  For  the  treatment  of  one  hundred  fowl,  about  one 
pound  of  the  powder  will  be  required. 

As  the  lice  are  likely  to  be  dislodged  from  their  hosts  to  be  harbored 
for  a  time  about  nests,  roosts,  etc.,  it  is  essential  that  the  eradicative 
measures  be  also  applied  to  the  quarters  of  infested  birds.     The  louse 


LICE  OF  POULTRY.     THE  BEDBUG  89 

most  commonly  fomid  upon  the  hen,  Menopum  trigonocephalum,  is  an 
especially  active  runner,  readily  passing  to  other  species  of  birds  or  to 
any  object  with  which  the  infested  animal  is  in  contact.  It  is  said  that 
horses  kept  in  the  vicinity  of  chicken  houses  harboring  this  louse  are 
often  seriously  troubled  by  it. 

In  this  connection  the  measures  recommended  for  the  eradication  of 
the  lice  of  mammals  and  poultrj'-infesting  bedbugs  will  in  general 
apply  here.  All  nesting  material  and  litter  must,  of  course,  be  cleared 
out  and  burned  or  buried.  A  washing  down  with  five  per  cent,  creolin 
or  carbolic  acid  solution  should  follow,  the  usual  whitewashing  in  such 
cases  adding  to  the  probability  of  a  complete  destruction  of  the  lice. 
The  lime  and  sulphur  mixture  (page  125),  apphed  as  a  spray  to  all  parts 
of  the  interior,  is  penetrating  and  gives  satisfactory  results. 

As  a  simple  agent  for  the  killing  of  lice  or  mites  in  the  hen  house  and 
dovecot  the  cloud  of  lime  dust  is  said  to  be  of  much  value.  In  the  appli- 
cation of  this  method  the  birds  should  be  absent  and  the  quarters  closed. 
A  few  handfuls  of  finely  powdered  lime  are  then  thrown  against  the  roof 
and  walls,  producing  a  cloud  of  dust.  This  will  settle  upon  the  roosts, 
nest  compartments,  and  floor,  and  into  the  crevices,  destroying  many  of 
the  exposed  vermin.  Afterward  the  place  should  be  swept  out  and  the 
sweepings  buried,  burned,  or  otherwise  destroyed. 

Fumigation  is  commonly  resorted  to,  and  may  have  value  as  a  con- 
tributory measure.  The  sulphur  fumigation,  applied  as  recommended  in 
the  eradication  of  bedbugs,  will  serve  here  as  well. 

Observations  made  as  to  the  length  of  time  required  for  the  hatching 
of  the  eggs,  while  not  complete,  indicate  that  for  species  of  bird  lice  in 
general,  five  to  six  days  are  necessary  at  least.  Therefore,  in  repeating 
treatments  intended  to  kill  individuals  hatched  from  remaining  eggs, 
there  should  be  an  intervening  period  of  about  ten  days. 

Order  V.    Hemiptera 

Insecta  (p.  15). — This  group  includes  the  cicadas,  plant  lice,  and  true 
bugs.  The  mouth  parts  are  suctorial,  the  mandibles  and  maxillae  being 
modified  into  bristle-Hke  structures  for  puncturing  and  extracting  the 
juices  of  plants  or  the  blood  of  animals.  The  labium  is  usually  jointed 
and  forms  a  sheath  for  the  piercing  bristles.  There  are  usually  four 
wings,  some  fomis  having  the  first  pair  thickened  and  leathery  at  the 
base,  while  only  the  tips  are  membranous  and  elastic.  It  is  from  this 
"  half-winged  "  structure  that  the  order  derives  its  name.  In  some  of  the 
lower  forms  (bedbugs)  wings  are  absent.  A  characteristic  of  the  order  is 
the  presence  of  stink  glands,  which  in  the  adult  open  ventrally  on  the 
metathorax.  The  secretion  from  these  glands  has  a  disgusting  odor, 
probably  originally  of  defensive  service  to  the  insect  though  in  parasitic 
forms  rather  serving  to  reveal  their  presence  and  location.    The  meta- 


90  PARASITES  OF  THE  DOMESTIC  ANIMALS 

morphosis  is  incomplete,  the  immature  insect  resembling  the  adult  ex- 
cept in  the  absence  of  wings. 

Family  Cimicid^ 

Hemiptera  (p.  89).  Bedbug  and  allies. — The  body  is  much  flat- 
tened and  is  ovate  in  outline.  The  adults  are  reddish  brown  in  color ; 
young  yellowish  white.  AVhen  full  grown  they  are  from  one-sixth  to  one- 
fifth  of  an  inch  in  length.  The  mouth  parts  inclose  long  slender  stylets 
(Fig.  61,  d).    Ocelli  are  absent.    Wing-covers  rudimentary  (Fig.  61,  c). 

CiMEx  Lectularius 

Acanthia  lectularia.  The  common  bedbug.  (Fig.  61). — Cimicidse 
(p.  90).  The  body  is  covered  with  short  hairs;  rostrum  short;  third 
and  fourth  joints  of  antennae  much  thinner  than  first  and  second;  second 
segment  of  antennae  shorter  than  third. 

The  eggs  are  oval,  pearly-white,  and  about  a  millimeter  in  length. 
The  young  leave  the  egg  by  a  small  operculum  at  the  end.  The  female 
deposits  from  one  hundred  to  two  hundred  eggs  in  cracks,  crevices,  and 
seams  of  beds  and  bedding,  beneath  loose  portions  of  wall-paper,  base- 
boards, floor  spaces,  and  similar  retreats. 

Hatching  occurs  in  about  one  week.  Development  from  the  nymphal 
to  the  adult  stage  will,  under  favorable  conditions,  occupy  about  six 
weeks.  The  time  required  for  the  development  of  adults  from  deposited 
eggs  under  such  conditions  may,  therefore,  be  approximated  at  from 
seven  to  eight  weeks. 

Habits  and  Effect  of  Bite. — In  their  feeding  habits  bedbugs  are 
nocturnal,  hiding  in  their  darkened  retreats  during  the  day  and  coming 
forth  at  night  to  crawl  upon  the  legs,  arms,  neck,  or  other  unprotected 
parts  of  their  victims,  where  they  will  feed  to  repletion.  After  this  en- 
gorgment  the  insects  will  retreat  to  their  usual  haunts  to  remain  for 
several  days,  during  which  time  the  meal  is  digested. 

The  effect  of  the  bite  of  the  bedbug  varies,  depending  upon  the  sus- 
ceptibihty  of  the  one  attacked.  In  some  it  produces  marked  irritation 
with  more  or  less  sweUing;  others  may  not  be  made  aware  of  its  presence. 
The  inflammation  experienced  by  sensitive  persons  seems  to  result 
mainly  from  the  puncture  of  the  skin.  The  biting  organ  is  like  that  of 
other  hempiterous  insects;  there  are  four  piercing  filaments  within  the 
labium  which  is  closely  applied  to  the  point  of  puncture  as  the  blood  is 
drawn  up. 

The  degree  to  which  the  insect  may  injure  other  animals  than  man  is 
somewhat  obscure.  Probably  the  same  or  closely  allied  species  to  those 
attacking  man  attack  animals  in  the  same  manner.     Chickens  are  es- 


LICE  OF  POULTRY.     THE  BEDBUG 


91 


92  PARASITES  OF  THE  DOMESTIC  ANIMALS 

pecially  likely  to  be  their  hosts,  the  usual  quarters  of  poultry  affording 
an  ideal  harbor  for  such  pests. 

Control. — Bedbugs  may  be  easily  carried  upon  clothing,  therefore 
puljlic  conveyances  and  places  where  people  of  all  sorts  and  conditions 
of  living  may  congregate,  afford  a  common  means  for  their  dissemina- 
tion. They  are  highly  prolific,  and  the  introduction  of  a  single  egg- 
bearing  female  may  be  sufficient  to  start  a  colony  of  bedbugs  within  a 
few  months. 

Eradication  is  made  somewhat  difficult  by  the  parasite's  habit  of 
seeking  hiding  places  during  the  day,  therefore  anything  used  for  this 
purpose  must  be  of  such  a  nature  that  it  will  penetrate  into  cracks, 
crevices,  joints  of  bedsteads,  mattress  seams,  and  all  such  places  where 
the  gregarious  insects  are  in  the  habit  of  assembling  and  depositing 
their  eggs.  Powders,  such  as  pyrethum,  are  of  practically  no  value  as 
they  are  not  sufficiently  penetrating.  One  of  the  best  remedies  is  kero- 
sene, applied  with  a  feather,  or,  better,  with  an  ordinary  machine  oiler. 
Benzene  is  as  effectual  and  will  volatilize  more  readily,  but  must  be 
used  with  great  caution  against  ignition.  A  solution  of  corrosive  sub- 
limate in  alcohol  may  also  be  used  with  good  results.  Fumigation  is  of 
doubtful  value,  though  flowers  of  sulphur,  two  pounds  to  each  one 
thousand  cubic  feet  of  room  space,  has  been  recommended  for  this  pur- 
pose. The  sulphur  should  be  placed  in  a  heap  in  a  pan,  a  depression 
made  in  the  top,  and  a  small  quantity  of  alcohol  poured  into  this  to 
facilitate  burning.  The  container  should  be  placed  in  a  larger  pan  and 
surrounded  by  water  as  a  precaution  against  fire.  During  fumigation 
the  room  should,  of  course,  be  tightly  closed.  Fumigating  with 
formaldehyde  gas  is  as  useless  against  bedbugs  as  it  is  against  other 
insects. 

Whatever  remedy  may  be  applied,  thoroughness  is  essential  to  success. 
Beds  and  bedding  should  be  inspected  daily,  and  all  places  where  the 
bugs  may  have  found  a  hiding  place  repeatedly  treated.  There  will  be 
less  difficulty  if  brass  and  iron  bedsteads  are  used,  the  old-fashioned 
wooden  bedsteads  furnishing  many  retreats  into  which  the  bugs  can 
force  their  flat,  thin  bodies. 

In  infested  chicken  houses  the  parasites  usually  secrete  themselves 
around  the  ends  of  the  roosts  and  in  the  nests.  Their  attack  upon  the 
chickens  at  night  results  in  a  loss  of  flesh  with  reduced  egg  production. 
In  heavy  infestation  chickens  will  often  die  from  emaciation  and  loss 
of  blood.  If  the  propagation  of  the  bugs  in  the  chicken  houses  is  not 
checked,  they  may  spread  to  nearby  buildings  to  become  a  source  of 
annoyance  to  other  live  stock. 

Control  measures  in  such  cases  consist  in  thoroughly  renovating  the 
chicken  house.  Roosts  in  wooden  fittings  should  be  taken  down,  and 
all  loose  lumber,  useless  boxes,  straw,  or  other  material  affording  hiding 


LICE  OF  POULTRY.    THE  BEDBUG  93 

places  removed  and  burned.  Possible  breeding  places  remaining  should 
be  sprayed  with  kerosene  or  kerosene  emulsion  (page  48).  Scalding 
hot  water  or  whitewash  will  destro}-  both  the  insects  and  the  eggs.  The 
kerosene  application  should  be  repeated  at  frequent  intervals  to  insure 
the  eradication  of  followmg  generations. 


^ 


^OJuy^ 


CHAPTER  X 

THE  MITES 

Class  II.  Arachaida.  Arthropoda  (p.  13). — The  arachnids  may  at 
once  be  distinguished  from  the  insects  by  the  relationship  of  the  body 
parts  and  the  number  of  ambulatory  appendages,  as  to  be  described. 

The  regions  of  the  body  are  more  or  less  fused,  the  head  being  com- 
monly fused  with  the  thorax  to  form  the  cephalothorax  (Fig.  62) , 

The  abdomen  is  in  some  forms  segmented  (scorpions),  in  others  un- 
segmented  and  separated  from  the  thorax  by  a  deep  construction  (true 
spiders). 

Sometimes  the  cephalothorax  and  abdomen  are  fused  into  one  un- 
segmented  body  (ticks  and  mites) . 

In  the  adult  there  are  four  pairs  of  locomotor  appendages,  usually 
seven-jointed,  attached  to  the  cephalothorax.     There  are  no  wings. 

Antennae  are  absent. 

The  mouth  parts  are  paired  chelicerse  and  pedipalpi,  the  first  in  front 
of  the  mouth,  the  second  to  the  side. 

The  chelicerse  are  short,  consisting  of  two  or  three  joints.  The  last 
joint  may  have  a  claw-like  termination  for  piercing  and  introducing 
poison  into  prey  (spiders),  or  it  may  be  in  the  form  of  small  chelae  (scor- 
pions). 

The  pedipalpi  are  longer  and  more  like  the  appendages  for  locomo- 
tion.   The  terminal  segment  may  be  strongly  chelate  (scorpions). 

The  eyes  are  located  anteriorly  upon  the  cephalothorax  and  consist 
of  a  varying  number  of  ocelli.    The  eyes  are  never  compound. 

The  skin  is  of  a  leathery  consistency  and  is  not  so  hard  as  in  insects. 

Respiration  is  either  by  tracheae  or  by  so-called  book-lungs,  the  latter 
consistmg  of  a  series  of  invaginations  of  the  skin  closely  applied  like  the 
leaves  of  a  book.  Either  one  or  both  of  these  forms  of  respiratory  organ 
may  occur  in  a  single  individual. 

Most  arachnids  are  oviparous.  In  aberrant  forms,  as  Linguatulida  and 
Acarina,  certain  adult  appendages  are  acquired  after  a  molt. 

The  class  Arachnida  includes  the  scorpions,  spiders,  ticks,  and  mites. 

The  two  parasitic  orders  are  Acarina,  which  includes  the  ticks  and 
mites,  and  Linguatulida,  containing  the  species  Linguatula  rhinaria. 

Order  I.  Acarina.  Ticks  and  Mites. — Arachnida  (p.  94).  These  are 
small,  freciuently  microscopic,  arachnids  iii  which  there  is  generally  no 
distinct  demarcation  l^etween  the  cephalothorax  and  abdomen,  the  body 
regions  being  massed  into  one. 


THE  MITES  95 

Due  to  parasitism,  the  mites  have  undergone  considerable  modifica- 
tion, the  scab  mites  are  without  ej-es  or  organs  of  respiration,  and  gener- 
ally the  tips  of  the  feet  are  terminated  by  suckers  or  bristles. 

In  the  larval  stage,  the  Acarina  have  but  three  pairs  of  legs,  the  fourth 
pair  appearing  behind  the  third  after  a  molt. 

The  mouth  parts  are  modified  into  a  beak-like  structure  for  piercing 
and  sucking. 

The  sexes  are  separate  and  reproduction  is  by  eggs  which  are  extruded 
from  the  genital  pore  situated,  as  in  other  Arachnida,  anteriorly  on  the 
ventral  surface  of  the  abdomen.  In  the  scab  mites  (Sarcoptidse)  the  fe- 
males are  provided  with  a  second  genital  opening,  the  copulating  vagina, 

G  J     M 


Fig.  62. — Diagram  of  the  anatomy  of  a  spider:  a,  anus;  b,  cecum  of 
mesenteron;  b',  its  anterior  end;  b",  branches  of  cecum  extending  into 
legs;  c,  cerebral  ganglion  connected  with  ventral  ganglionic  mass;  d, 
mesenteron;  e,  poison  glands;  g,  heart;  h,  chelicerae;  i,  pedipalpi;  j,  liver; 
k,  hepatic  duct;  1,  lung  sac;  m,  Malpighian  tubules;  n,  dilation  of  rectum 
into  which  Malpighian  tubules  open;  o,  eyes;  ov,  ovaries;  p,  female 
genital  pore;  q,  large  and  small  silk  glands;  r,  opening  of  tracheal  system; 
s,  spinnerettes  (after  Boas  by  Kirkaldy  &  Pollard). 

which  is  located  posteriorly  just  in  front  of  the  anus.  It  is  at  this  open- 
ing that  spermatozoa  are  received  during  copulation,  the  anterior  open- 
ing serving  as  the  pore  of  the  oviduct. 

In  their  development  the  Acarina  undergo  a  succession  of  stages.  The 
larvae  are  usually  provided  with  but  three  pairs  of  legs  (hexapodal),  and 
have  no  definite  sexual  characters.  After  molting  a  fourth  pair  of  legs 
appears,  and  the  acarus  enters  upon  its  njanphal  stage.  Following 
further  molting  the  genital  organs  are  acquired,  and  it  has  then  reached 
the  pubescent  stage,  or  stage  of  sexual  maturity.  After  copulation  the 
female  undergoes  a  further  transformation,  l^ecoming  an  egg-bearing, 
or  ovigerous  female. 

Parasitism. — The  majority'  of  the  Acarina  are  parasitic,  though,  as 
to  this  habit,  there  is  much  diversity,  some  being  semiparasitic,  others 
essentially  so  and  restricted  to  definite  hosts. 

The  order  contains  a  number  of  families  of  which  the  following  are 
here  considered: 


96  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Famil}^  I.  Gamasidae. — Poultry  mites. 

Family  II.  Trombidiidae. — Harvest  mites  or  chiggers. 

Family  III.  Sarcoptidse. — Mange  and  scab  mites. 

Family  IV.  Demodecidae. — Follicle  mites. 

Family  V.  Cytoleichidse. — Deep  seated  mites  of  birds. 

Superfamily  Ixodoidea. — The  ticks. 

Family  I.  Argasidce. — The  fowl  tick  and  ear  tick. 

Family  II.  Ixodidge. — The  cattle  tick  and  other  ticks. 

Each  of  these  contains  species  parasitic  upon  mammals  or  birds  with 
the  exception  of  the  Demodecidae,  which,  so  far  as  known,  have  only 
been  found  upon  mammals. 

The  condition  produced  upon  the  host  by  the  presence  of  parasitic 
Acarina  is  designated  medically  as  acariasis.  Differing  in  their  grade 
of  parasitism,  the  numerous  species  bring  about  a  varying  degree  of 
disturbance  to  the  skin  which  they  inhabit.  Accordingly  there  is  dis- 
tinguished sarcoptic  and  psoroptic  acariasis,  the  former  produced  by 
species  which  burrow  and  form  subepidermic  galleries  in  which  they 
deposit  their  eggs,  the  latter  by  species  living  upon  the  skin's  surface. 
The  term  mange  is  limited  by  most  writers  to  acarises  caused  by  species 
of  the  genus  Sarcoptes  and  its  near  alKes,  or  by  Demodex,  both  living 
beneath  the  skin's  surface,  the  last  named  in  the  hair  follicles  and  se- 
baceous glands.  The  psoroptic  form,  in  which  there  is  deep  scab  for- 
mation, constitutes  true  scabies  or  scab,  although  these  latter  terms  are 
frequently  used  in  a  general  sense  relative  to  the  condition  produced 
by  the  mange  and  scab  mites.  Acari  belonging  with  the  families  Ga- 
masidae, Trombidiidae,  and  the  superfamily  Ixodoidea  do  not  cause 
mange  or  scab. 

Classification  of  Parasites  of  the  Class  Arachnida 

Class  B.    Arachnida.    P.  94. 
Order  I.    Acarina.    P.  94. 
Family  (a)  Gamasidae.    P.  98. 
Genus  and  Species: 

Dermanyssus  gallinae.    Host,  poultry.    P.  98. 
Family  (b)  Trombidiidae.    P.  99. 
Genus  and  Species: 

Trombidium   holosericeum.      Larvae   attack  man   and   lower 
animals.    P.  100. 
Family  (c)  Sarcoptidae.    Mange  and  scab  mites.    P.  lOL 
Genus  and  species: 

Sarcoptes  scabiei  var.    Equi.     Host,  equines.    P.  104. 
S.  scabiei  var.   'Ovis.    Host,  sheep.    P.  112. 
S.  scabiei  var.    Bovis.    Host,  cattle.    P.  114. 
S.  scabiei  var.    Suis.    Host,  hog.    P.  114. 


THE  MITES  97 

S.  scabiei  var.    Canis.    Host,  dog.    P.  115. 
Notoedres  cat!  var.    Cati.    Host,  cat.    P.  118. 
N.  cati  var.    Cuniculi.    Host,  rabbit.    P.  118. 
Psoroptes  communis  var.    Equi.    Host,  equiiies.    P.  108. 
P.  communis  var.    Ovis.    Host,  sheep.    P.  109. 
P.  communis  var.    Bovis.    Host,  cattle.    P.  113. 
P.  comnmnis  var.    Cuniculi.    Host,  rabbit.    P.  118. 
Chorioptes  commimis  var.    Equi.    Host,  equines.    P.  108. 
C.  communis  var.    Ovis.    Host,  sheep.    P.  112. 

C.  communis  var.    Bovis.    Host,  cattle.    P.  113. 
Otodectes  cynotis  var.    Canis.    Host,  dog.    P.  117. 

0.  cynotis  var.    Cati.    Host,  cat.    P.  117. 
Cnemidocoptes  mutans.    Host,  poultr}-.    P.  132. 
Cn.  gallinae.    Host,  poultry.    P.  133. 

Family  (d)  Demodecidae.    Folhcular  mange  mites.    P.  103. 
Genus  and  Species: 

Demodex  folliculorum  var.    Ovis.    Host,  sheep.    P.  112. 

D.  folhculorum  var.    Suis.    Host,  hog.    P.  115. 
D.  folliculorum  var.    Canis.    Host,  dog.    P.  116. 

Family  (e)  Cytoleichidae.    P.  134. 
Genus  and  Species: 

Cj'toleichus  nudus.    Host,  poultry.    P.  134. 
Laminosioptes  cysticola.    Host,  poultry.    P.  134. 
Superfamily  Ixodoidea.    Ticks.    P.  139. 
Family  (a)  Argasidse.    P.  139. 
Genus  and  Species: 

Argas  miniatus.    Host,  poultry.    P.  139. 
Otobius  megnini.    Hosts,  equines,  cattle,  etc.    P.  140. 
Family  (b)  Ixodidse.    P.  141. 
Genus  and  Species: 

Ixodes  ricinus.    Hosts,  cattle,  equines,  dog,  etc.    P.  143. 

1.  hexagonus.    Hosts,  cattle,  dog,  etc.    P.  143. 
Dermacentor    variabilis.     Hosts,    cattle,    dog,    equines,    etc. 

P.  143. 
D.  reticulatus.    Hosts,  cattle,  equines,  etc.    P.  143. 
Margaropus  annulatus.    Hosts,  cattle,  equines.    P.  144. 
Amblvomma  americanum.     Hosts,  cattle,  dogs,  equines,  etc. 
P.  i45. 
Order  2.    Linguatulida.    P.  153. 
Family  (a)  Linguatulidse.    P.  153. 
Genus  and  Species: 

Linguatula  rhinaria.    Host,  dog.    P.  153. 


98 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Family  I.   Gamasid^e 

Acaiiiia  (p.  94). — The  gamasid  mites.  The  mouth  parts  are]  ar- 
ranged for  piercmg  and  sucking,  maxillae  fused  into  a  tube,  maxillary 
palps  five-segmented  and  provided  inwardly  with  secondary  palps. 
The  legs  have  six  segments,  the  tarsi  terminating  b,y  two  booklets. 
There  are  two  stigmata  located  near  the  insertion  of  the  posterior  legs. 
The  cephalothorax  and  abdomen  are  fused  into  one  body.  The  integu- 
ment is  of  a  leatherv  texture.    Eves  are  absent. 


Dermanyssus  Gallin.e 

Poultry  mite;  chicken  "tick"  (Fig.  63).  Gamasidse  (p.  98). — Body 
somewhat  egg-shaped  with  larger  end  posterior,  slightly  flattened  from 
above  to  below.     The  lower  half  of  the  body  is  provided  with  short, 


Fig.  63. — Dermanyssus  gallinae:  a,  adult;  b,  tarsus;  c,  mouth- 
parts;  d  and  e,  young — all  enlarged  (after  Osborn,  Bull.  No.  5,  Bureau 
of  Entomology,  U.  S.  Dept.  of  Agr.). 

well-separated  bristles.  The  color  is  Hght  gray  with  dark  patches 
showing  through  the  skin;  when  engorged  with  blood  the  color  is  a 
distinct  red.    The  ovigerous  female  is  rather  less  than  1  mm.  in  length. 

Occurrence  and  Habits. — The  little  poultry  mite,  found  everywhere 
where  chickens  are  kept,  is  one  of  the  most  persistent  and  injurious  pests 
that  the  poultry  raiser  has  to  contend  with.  Remaining  in  darkened 
retreats  about  the  henhouse  during  the  daytime,  these  acari  come  forth 
at  night  to  swarm  upon  the  fowls  and  suck  their  blood.  Their  attack, 
however,  is  not  confined  entirely  to  the  night,  and  hens  may  be  driven 


THE  MITES  99 

from  their  nests  by  the  activity  of  the  pests  which  the  warmth  of  their 
bodies  creates. 

The  Demianyssiis  does  not  hmit  itself  to  birds,  but  may  attack 
mammals,  including  man,  though  these  animals,  being  accidental  hosts, 
the  invasion  is  usually  limited  in  its  extent  and  duration.  Horses  kept 
in  the  vicinity  of  infested  henhouses  are  likely  to  be  tormented  by  the 
mites,  the  litter  about  stables  so  located  affording  a  harbor  to  which 
they  readily  migrate. 

The  eggs  are  deposited  in  vast  numbers  in  the  daytime  retreats. 
Under  ordinary  conditions  about  five  days  are  required  for  the  hatching 
of  the  hexapodal  larvae  which  do  not  wait  for  maturity  to  attack  the 
chickens.  They  may,  however,  remain  for  months  without  a  host  upon 
which  to  satisfy  their  appetite  for  blood.  Extremely  prolific,  they 
especially  thrive  upon  filth,  and  large  colonies  may  be  found  wherever 
such  material  has  collected. 

Effect. — ^Fowls  suffer  not  only  from  the  extreme  irritation  and  an- 
noyance of  the  attack,  but  additionally  from  the  extraction  of  a  consider- 
able amount  of  blood.  Prolonged  infestation  must  essentially  brine; 
about  a  progressive  emaciation  and  weakening  which  may  end  in  death, 
young  chicks  especially  being  likely  to  succumb.  In  any  event  egg 
production  is  retarded,  and  the  chickens,  in  their  unthrifty  condition, 
are  unprofitable  for  marketing. 

Control. — Cleanliness  and  plenty  of  sunlight  are  especially  antago- 
istic  to  the  Dermanyssus.  The  cleaning  up  measures  set  forth  elsewhere 
for  the  eradication  of  the  parasites  of  the  henhouse  need  not  be  repeated 
here.  Kerosene  emulsion  (page  48)  is  serviceable,  but  should  only  be 
applied  after  the  entire  interior  has  been  stripped  to  the  boards  of  every- 
thing movable  and  all  crevices,  joints,  and  roost  insertions  exposed. 
It  is  well  to  drench  cracks  and  the  ends  of  roosts  with  pure  kerosene  or 
scalding  water.  The  ends  of  roosts,  before  being  replaced,  should  be 
dipped  in  coal  tar,  and  this  spread  along  the  roosts  for  about  six  or  eight 
inches  from  their  supports  in  such  manner  that  the  mites  will  be  obliged 
to  cross  the  tar  before  reaching  the  fowls.  Pyrethrum  powder,  alone  or 
mixed  with  lime  dust,  should  be  shaken  through  the  fresh  nesting  mate- 
rial. The  dust  bath,  as  recommended  in  the  treatment  for  lice,  should 
always  be  accessible. 

In  order  to  insure  continued  freedom  from  the  vermin  it  is  necessary 
that  the  control  measures  be  repeated  at  least  three  times  at  intervals 
of  about  ten  days. 

Family  II.  Trombidiid^ 

Harvest  mites;  chiggers,  or  red  bugs.  Acarina  (p.  94). — The  body  is 
red  in  color  and  covered  with  bristles  or  fine  hairs.  The  mandibles  are 
chelate;  palpi  prominent.     The  legs  have  six  to  seven  segments  pro- 


100  PARASITES  OF  THE  DOMESTIC  ANIMALS 

vided  with  bristles  or  fine  hairs,  the  tarsi  terminating  in  two  hooklets. 
Respiration  is  by  tracheae.  There  are  two  eyes,  one  located  upon  each 
side  of  the  cephalothorax. 

Trombidium  Holosericeum 

Trombidiidse  (p.  99). — Body  red  and  nearly  square;  slightly  narrower 
posteriorly  where  the  terminal  border  is  slightly  concaved;  body  and 
legs  covered  with  bristly  hairs.  Eyes  pedunculated.  About  1  mm.  in 
length. 

Habits  and  Effect. — In  the  adult  stage  the  Trombidium  is  free- 
living,  feeding  upon  the  juices  of  plants  and  small  insects.  It  is  only 
parasitic  in  its  larval  condition,  in  which  stage  it  will  inhabit  insects 
and  attack  warm-blooded  animals  as  well.  Living  in  the  tall  grass  and 
upon  the  under  side  of  the  leaves  of  weeds,  they  are  brushed  off  upon 
the  hands  or  clothing  of  people  and  upon  the  bodies  of  animals  as  they 
pass  through  the  vegetation.  They  then  proceed  to  burrow  into  the 
skin,  setting  up  a  most  exasperating  itching  with  the  formation  of 
reddened  patches  often  covering  considerable  areas.  This  phase  of 
the  mite's  parasitism  is  pecuhar  in  that  it  invariably  perishes  in  the  act 
of  entering  the  skin.  It  is  likely  to  be  most  troublesome  during  the  late 
summer  and  autumn,  the  name  Leptus  autumnalis,  under  which  the 
larval  stage  of  the  mite  has  been  described,  being  derived  from  this  fact. 

Man  is  most  often  attacked  about  the  lower  parts  of  the  legs  and  upon 
the  hands.  Among  domestic  animals,  those  which  frequent  locations 
densely  covered  with  vegetation  are  the  most  likely  to  suffer.  Hunting 
dogs  especially  are  exposed,  and  on  returning  from  the  field  will  often 
exhibit  symptoms  of  great  itching  about  the  face,  paws,  inner  thighs, 
and  belly,  the  parts  most  often  attacked.  Horses  will  be  affected  prin- 
cipally below  the  knees  and  hocks. 

Treatment. — As  the  larval  mites  die  upon  entering  the  skin,  the 
source  of  the  irritation  is  soon  eliminated  and  the  intense  itching  will 
usually  rapidly  subside,  leaving  areas  of  epithelial  exfoliation  over  the 
parts  affected.  Recently  exposed  animals  will  be  relieved  somewhat  by 
frictions  with  a  cloth  sprinkled  with  benzene,  or  by  the  application  of  a 
mixture  of  equal  parts  of  hme-water  and  hnseed  oil,  or  sulphur  ointment 
may  be  used.  Sponging  with  a  solution  of  carbolic  acid  at  about  three 
per  cent,  strength  in  water  to  which  a  little  glycerin  has  been  added, 
will  do  much  toward  reheving  the  itching.  Ammonia-water,  or  a  solu- 
tion of  bicarbonate  of  soda  are  both  of  value  for  this  purpose. 

Persons  working  or  passing  through  infested  districts  will,  in  con- 
siderable degree  at  least,  be  protected  from  attack  by  applying  a  mix- 
ture of  kerosene  and  glycerin  to  the  hands  and  ankles. 


THE  MITES  101 

Family  III.  Sarcoptid^ 

Mange,  scab,  or  itch  mites.  Acarina  (p.  94). — The  body  has  the 
cephalothorax  and  abdomen  fused ;  it  is  white  or  reddish  in  color.  The 
ciiticular  surface  is  transversely  striated  and  provided  with  bristles, 
sometimes  with  short  dorsal  spines.  The  mouth  parts  are  beak-like, 
extending  forward,  and  covered  by  the  protruding  labrum;  chelicerae 
scissors-hke;  maxillary  palpi  small  and  three-segmented.  The  legs  are 
short  and  stout,  have  five  segments,  and  are  disposed  in  two  groups  of 
two  pairs  each,  the  anterior  pairs,  usually  the  larger  and  near  the  mouth 
parts,  the  posterior  pairs  near  the  abdomen.  The  tarsi  commonly  ter- 
minate in  one  or  two  booklets;  they  may  temiinate  in  a  long  bristle  or 
an  ambulator}^  sucker,  often  upon  a  stalk  which  may  be  segmented. 
Respiratory  organs  are  absent;  respiration  cutaneous.  There  are  no 
eyes.    All  are  scarcely  visible  without  the  aid  of  magnification. 

There  are  frequently  well-marked  sexual  differences.  ]Males  are  con- 
siderably smaller  than  the  females.  In  some  males  the  fourth  pair  of 
legs  is  very  small,  and  there  may  be  plate-like  copulatory  suckers  at 
the  base  of  the  abdomen  with  abdominal  prolongations.  As  to  the 
presence  or  absence  of  bristles  or  stalked  suckers,  the  tarsi  ma}^  ter- 
minate differently  in  the  two  sexes. 

Development. — As  already  stated  in  the  general  reference  to  the 
Acarina,  the  Sarcoptidae  have  three  distinct  stages  in  the  development  of 
the  male,  four  in  the  female.  After  sexual  maturity  and  fertihzation  of 
the  female,  the  male  usually  dies.  Following  fertilization  the  female 
molts  and  enters  upon  her  fourth  or  ovigerous  stage, — the  egg-bearing 
stage,  recognizable  by  the  presence  of  the  genital  pore  upon  the  anterior 
ventral  surface  of  the  abdomen,  through  which  the  eggs  are  extruded. 

The  rapidit\'  with  which  these  acari  breed  is  very  great.  It  has  been 
estimated  that  one  female  sarcopt  will  produce  in  a  subepidermic  gallery 
about  fifteen  individuals,  from  which,  after  ninety  days,  there  may  be 
1,500,000  descendants  constituting  the  sixth  generation. 

The  family  includes  a  number  of  genera  differing  in  their  mode  of 
attack  and  location  upon  the  host.  All  are  permanently  parasitic.  Of 
these,  sLx,  nameh"  Sarcoptes,  Psoroptes,  Chorioptes,  Notoedres,  Cnem- 
idocoptes,  and  Otodectes  are  considered  here.  The  characteristics  and 
habits  of  the  principal  genera  met  with  follow. 

Sarcoptes  (Fig.  64).  Sarcoptidae  (p.  101). — The  body  is  rounded  or 
slighth'  oval;  the  mouth  parts  short  and  about  as  broad  as  long.  Upon 
the  dorsal  surface  of  the  body  are  a  number  of  cone-like  prominences 
and  twenty  spines,  the  latter  short,  thick,  and  grouped  as  follows:  four- 
teen upon  the  abdomen,  seven  to  the  right  and  seven  to  the  left  side; 
six  upon  the  cephalothorax,  three  to  the  right  and  three  to  the  left. 
The  legs  are  thick  and  conical,  the  posterior  pair  being  nearly  or  quite 


102  PARASITES  OF  THE  DOMESTIC  ANIMALS 

concealed  beneath  the  abdominal  margin  when  the  acarus  is  in  dorsal 
view.  In  the  female  the  first  two  pairs  of  legs  are  terminated  by  stalked 
ambulatory  suckers;  the  posterior  pairs  by  bristles.  In  the  male  all 
of  the  legs  are  provided  with  stalked  suckers  but  the  third  pair  which 
terminates  in  bristles.  The  anus  is  located  upon  the  posterior  dorsal 
margin  of  the  abdomen.  Just  anterior  to  this  in  the  female  is  the  copu- 
lating vagina  (receptaculum  seminis).  Upon  the  ventral  side  at  the 
median  anterior  border  of  the  abdomen  of  the  ovigerous  female  is  the 
genital  pore.  The  males  have  no  copulatory  suckers  or  abdominal  ex- 
tensions. 

The  Sarcoptes  live  upon  man  and  practically  all  of  the  domestic 
mammals.  In  the  latter  animals  they  seek  the  parts  of  the  body  where 
the  hair  is  short,  while  in  man  their  preference  is  for  places  where  the 
skin  is  thin,  as  about  the  kimckles,  between  the  fingers,  and  in  the  bend 
of  the  elbows  and  knees.  A  peculiarity  of  their  attack  is  the  habit  in 
the  female  of  cutting  tunnels  beneath  the  epidermis,  in  the  bottom  of 
which  she  deposits  her  eggs  (Fig.  65),  a  circumstance  that  renders  this 
form  of  acariasis  relatively  difficult  to  cure. 

The  Sarcoptes  inhabiting  the  skin  of  various  animals  cannot  be  said 
t  o  exhibit  differences  of  specific  importance.  They  may,  therefore,  be 
placed  in  a  single  species — Sarcoptes  scahiei — which  may  give  rise  to 
varieties  according  to  host,  as  Sarcoptes  scahiei,  var.  homi7iis  of  man,  var. 
equi  of  the  horse,  and  var.  suis  of  swine,  etc.  The  slight  difference  in 
these,  as  in  other  Sarcoptidae,  is  mainly  one  of  size. 

Psoroptes  (Figs.  68  and  69).  Sarcoptida  (p.  101).— The  body  is 
oval,  the  mouth  parts  elongated  and  in  the  form  of  a  cone.  The  legs 
of  the  anterior  pairs  are  thick,  the  posterior  pairs  more  slender;  all  four 
pairs  extend  beyond  the  margin  of  the  body.  In  the  female  the  first 
two  pairs  of  legs  and  the  fourth  pair  are  terminated  by  ambulatory 
suckers  carried  on  long,  three-segmented  stalks,  the  third  pair  being 
terminated  by  bristles.  The  male  has  copulatory  suckers  serving  for 
fixation  to  the  female,  and  short  posterior  al^dominal  prolongations 
terminated  by  bristles.  The  first  three  pairs  of  legs  are  terminated  by 
stalked  suckers;  the  fourth  pair  is  stunted. 

Psoroptic  scabies,  the  form  produced  by  the  members  of  this  genus, 
is  the  most  common  and  has  been  longest  known.  Unlike  Sarcoptes, 
Psoroptes  seek  the  parts  of  the  body  where  the  hair  is  long;  they  do  not 
burrow  beneath  the  epidermis,  but  attack  the  skin  upon  its  surface, 
their  punctures  being  followed  by  the  formation  of  thick  crusts.  Under 
these  they  live  in  colonies  which  may  coalesce  and  eventually  cover 
areas  of  the  bod}--  more  or  less  circumscribed.  Psoroptic  scabies  is  most 
often  observed  upon  animals  with  bodies  covered  wholly  or  in  part  by 
long  hair,  as  the  sheep,  ox,  and  horse. 

As  with  Sarcoptes,  the  difference  in  host  inhabited  by  Psoroptes 


THE  MITES  103 

coincides  with  varieties  which  have  unimportant  and  scarcely  dis- 
tinguishable differences.  There  is,  therefore,  but  one  species,  Psoroptes 
communis,  designated  according  to  host  as  variety  ovis  of  the  sheep, 
var.  bovis  of  the  ox,  var.  equi  of  the  horse,  var.  cuniculi  of  the  rabbit, 
etc. 

Chorioptes  (Symbiotes;  Dermatophagus)  (Fig.  67).  Sarcoptidae 
(p.  101). — The  body  is  oval.  The  mouth  parts  are  about  as  broad  as 
long  and  somewhat  dome-shaped.  The  legs  are  long  and  visible  beyond 
the  sides  of  the  body.  The  ambulatory  suckers  are  large  and  carried  on 
short,  unsegmented  stalks.  In  the  female  all  of  the  legs  are  terminated 
by  suckers  excepting  the  third  pair,  these  are  terminated  by  bristles. 
The  male  has  copulatory  suckers  and  abdominal  prolongations  ter- 
minated by  leaf-like  processes.  The  fourth  pair  of  legs  is  stunted;  all  of 
the  legs  are  provided  with  suckers. 

Chorioptic  mites  live,  as  do  psoroptic,  in  colonies  upon  the  skin  where 
the  hair  is  long  and  among  the  crusts  which  they  form.  There  is  one 
species,  Chorioptes  communis  (Symbiotes  communis,  Chorioptes  symbiotes, 
Dermatophagus  communis).  This  infests  the  lower  parts  of  the  legs, 
especially  of  horses  with  long  hairs  upon  the  fetlocks,  though  in  the  ox 
this  form  of  scabies  generally  has  its  seat  at  the  base  of  the  tail. 

Cnemidocoptes  (Sarcoptes).  SarcoptidiP  (p.  101). — The  body  is 
rounded  in  outline.  The  mouth  parts  are  short,  broader  than  long,  and 
rounded.  In  the  female  the  legs  are  conical  and  very  short;  they  are 
without  suckers  or  bristles,  terminating  in  two  unequal  booklets.  In 
the  male  the  legs  are  somewhat  longer  and  all  four  pairs  are  terminated 
by  stalked  suckers  and  bristles. 

This  genus  contains  a  burrowing  mite,  Cnemidocoptes  mutans  (Fig.  74), 
which  produces  "scaly  leg"  in  fowls;  also  a  species  known  as  the  de- 
pluming mite,  Cnemidocoptes  gallince,  which  attacks  the  skin  of  fowls 
near  the  insertion  of  the  feathers. 

Of  the  genera  Notoedres  (Fig.  71)  and  Otodectes,  the  former  infests 
small  mammals,  and  the  latter  lives  in  the  external  ear  of  the  dog  and 
cat. 

Family  IV.  Demodecid.e 

Acarina  (p.  94).  Follicular  mange  mites  (Fig.  70).  These  are  verj' 
minute  and  worm-like.  The  body  is  distinctly  divided  into  cephalo- 
thorax  and  abdomen,  the  latter  elongated  and  transversely  striated. 
The  anus  is  on  the  anterior  ventral  border  of  the  abdomen,  probably 
serving  in  the  female  for  both,  copulation  and  ovulation.  The  legs  are 
three-segmented,  short  and  stumpy.  The  mouth  parts  are  suctorial. 
Respiration  is  cutaneous.  There  are  no  e.yes.  The  length  is  about 
0.3  mm. 

They  undergo  the  same  stages  of  development  as  other  acari. 


104 


PARASITES  OF  THE  DOMESTIC  ANIIVIALS 


There  is  but  one  species,  Demodex  follicidorum  (Fig.  70),  which  in- 
habits the  hair  folhcles  and  sebaceous  glands  of  several  manunalian 
species.  Its  size  differs  somewhat  with  its  habitat,  the  difference  in 
dimensions  authorizing  a  division  into  varieties  according  to  host. 

Scabies  of  the  Horse 
Horses,  asses,  and  mules  are  affected  with 'one  form  of  mange  and  two 
of  true  scabies,  as  follows : 

1.  Sarcoptic  mange,  due  to  Sar copies  scabiei  var.  equi. 

2.  Psoroptic  scabies,  due  to  Psoroptes  communis  var.  equi. 

3.  Chorioptic  scabies,  due  to  Chorioptes  communis  var.  equi. 
Sarcoptic  Mange  of  the  Horse. — In  the  majority  of  cases  acariasis  of 

the  horse  is  caused  by  Sarcoptes  (Fig.  64).    It  begins  most  frequently 


Fig.  64. — Sarcoptes  scabiei  var.  equi,  female;  dorsal  (left)  and  ventral 
(right)  surface. 

about  the  head,  sides  of  the  neck,  or  at  the  withers,  extending,  if  neg- 
lected, over  large  areas  of  the  body,  involving  in  some  cases  even  the 
lower  parts  of  the  legs.  In  its  initial  stage  sarcoptic  mange  is  somewhat 
slow  in  development,  the  small  number  of  acari  at  the  beginning  not 
giving  rise  to  s\miptoms  readily  observable.  In  from  three  to  six  weeks, 
however,  the  multiplication  of  the  parasites  has  sufficiently  progressed 
to  clearlj'  reveal  the  affection. 

Symptoms. — The  first  sjanptom  is  itching,  more  or  less  intense, 
which  the  animal  seeks  to  relieve  by  rubbing  itself  against  anything 
available,  or  by  biting  affected  parts  of  the  body  which  it  can  reach. 


THE  MITES 


105 


When  groomed  with  the  brush  or  currycomb  it  will  manifest  its  pleasure 
by  protrusion  and  movements  of  the  upper  lip,  at  the  same  time  leaning 
toward  the  brush.  This  action  is  not  peculiar  to  mange,  however,  as  it 
may  be  observed  in  any  itching  skm  affection  of  the  horse.  The  pruritus 
seems  to  be  greater  at  night  and  is  always  intensified  by  an  increase  in 
the  warmth  of  the  body,  as  hy  a  warm  stable  or  warm  clothing.  This  is 
probably  due  to  the  greater  activity  of  the  parasites  under  such  condi- 
tions. 

Lesions.^ — The  first  changes  in  the  skin  will  be  the  formation  of 
small  nodules,  which  ma}'-  be  felt  by  the  hand  as  it  is  passed  over  the 
skin's  surface.  At  these  locations  small  crusts  are  formed  about  the 
tufts  of  2natted  hairs,  which  are  easily  removed,  leaving  a  moist  and 
reddened  surface.  From  the  nodules  small  papules  develop,  the  epider- 
mis being  raised  by  the  subepidermic  serous  effusion.  These  rupture, 
and  the  desquamated  surface  gradually  dries,  leaving  a  scaly  formation 
upon  the  skin.  With  the  extension  of  these  lesions  the  hair  falls  out  in 
patches,  the  affected  areas  becoming  confluent  and  covered  by  dry 


Fig.  65. — Burrow  of  sarcopt  in  human  skin,  with  eggs  and  mite  (after 
Osborn,  from  Furstenburg  and  Murry;  Bureau  of  Entomology,  U.  S.  Dept. 
of  Agr.). 

epidermic  scales  and  thin  crusts.  Soon  following  upon  this  stage  the 
skin  thickens  and  forms  into  folds,  especially  over  the  parts  where  it  is 
freely  movable,  as  about  the  throat,  neck  and  breast.  When  these 
folds  are  separated  the  skin  between  them  is  found  to  be  in  a  raw  and 
purulent  condition,  bleeding  at  the  slight  touch  of  an  instrument  or 
of  the  finger  nail.  In  neglected  cases  the  body  may  become  almost 
entirely  denuded  of  hair  and  the  thickened  skin  covered  everywhere  with 
crusts,  bleeding  fissures,  and  ulcers,  the  animal  presenting  a  most 
miserable  appearance  (Fig.  66).  The  alterations  m  the  skin  are  not  all 
directly  brought  about  bj'  the  parasites,  being  contributed  to  by  the 
violent  rubbing  of  the  animal  in  its  efforts  to  relieve  the  itchmg.  Excoria- 
tions with  the  formation  of  hemorrhagic  exudations  and  ulcers  are  often 
an  accompaniment  from  this  cause. 

Diagnosis  and  Development. — AVith  these  symptoms  in  their  early 


106 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


or  late  stages,  the  diagnosis  of  sarcoptic  mange  may  be  made  positive 
by  the  recovery  of  the  Sarcoptes.  This  should  be  looked  for  as  soon  as 
the  presence  of  mange  is  suspected,  as  it  is  important  to  know  with  what 
form  of  the  disease  we  have  to  deal.  The  nymphte  and  pubescent  males 
and  females  live  upon  the  body  surface  and  among  the  crusts  over  all 
affected  parts.  Innnediately  after  they  become  impregnated  the  oviger- 
ous  females  burrow  galleries  beneath  the  epidermis  in  which  they  deposit 
their  eggs  and  live  for  a  time  with  the  young  larva?  (Fig.  65) .  In  man  the 
course  of  the  galleries  is  marked  by  fine  red  lines  from  8  to  15  mm.  or 
more  in  length,  but  in  the  horse  these  cannot  be  seen  owing  to  the 
thickness  and  pigmentation  of  the  epidermis.  The  sarcopt  is  usually 
lodged  at  the  extreme  end  of  the  channel  in  the  course  of  which  her  eggs 


Fig.  66. — Colts  affected  with  advanced  sarcoptic  mange  (from  author's  i)hotograph) 


are  distributed.  It  has  been  estimated  that  approximately  fifteen  in- 
dividuals will  be  produced  in  each  of  these  subepidermic  burrows,  and 
that  about  fifteen  days  are  required,  under  average  conditions,  for  their 
full  development  and  the  appea^rance  of  the  next  succeeding  generation. 
The  larvae  issuing  from  the  eggs  live  in  the  gallery  for  some  time  before 
finally  making  their  exit  along  its  course,  while  the  parent  female  soon 
dies  after  ovulation  is  completed.  Copulation  takes  place  upon  the 
skin  beneath  the  crusts,  the  males  dying  after  the  performance  of  this 
function.  As  the  males  are  also  relativeh^  less  in  number,  it  is  the  fe- 
males which  are  more  often  met  with. 

To  secure  the  parasite  for  examination  the  crusts  should  be  removed 
and  skin  scrapings  taken  in  such  a  manner  as  to  include  a  portion  of 
serous  exudate  with  the  epidermic  scales.  The  material  should  be  taken 
from  a  part  showing  evidences  of  recent  attack,  the  mites  being  more 
hkely  to  be  found  there  than  in  the  older  lesions.     This  material,  to- 


THE  MITES  107 

gether  with  a  few  flakes  from  the  deeper  portion  of  the  crust,  may  then 
be  placed  upon  a  gkiss  and  teased  in  glycerin.  After  having  been 
sufficiently  divided  and  spread  by  the  needles,  it  is  ready  for  examination 
under  the  low  power  of  the  microscope,  or  by  a  strong  hand  lens.  It  is 
often  necessary  to  thoroughly  search  several  preparations  before  finding 
the  acarus.  The  material  can  be  more  easily  teased  and  cleaned  up  if 
submitted  for  an  hour  or  two  to  the  action  of  a  five  to  ten  per  cent, 
solution  of  caustic  soda. 

A  method  commonly  used  in  the  Laboratory  of  the  Pennsylvania 
State  Bureau  of  Animal  Industry  for  the  detection  of  scab  acari  is  as 
follows:  Cover  the  material  with  a  ten  per  cent,  solution  of  sodium 
hydrate  and  set  aside  for  one  or  two  hours.  Heat  to  boiling  and  cen- 
trifuge for  twenty  minutes.  The  liquid  is  then  carefully  drawn  off, 
water  added,  and  the  sediment  shaken  up.  This  is  agam  centrifuged, 
water  drawn  off,  and  fresh  water  added  in  which  the  sediment  is  again 
washed  and  centrifuged.  The  sediment  is  then  thinly  spread  upon 
slides  and  examined  under  low  power.  By  this  treatment  the  scabs  and 
crusts  are  thoroughly  disintegrated.  Some  of  the  mites  may  also  be 
fragmental,  but  not  to  such  an  extent  as  to  prevent  recognition  of  the 
species. 

Prognosis. — Owing  to  its  great  contagiousness  and  the  difficulty  in 
reaching  the  parasites,  sarcoptic  acariasis  is  the  most  serious  of  the 
three  forms  which  may  affect  the  horse.  Early  in  its  course  the  con- 
stantly tortured  and  unpresentable  animal  becomes  unfit  for  work,  and, 
when  the  disease  is  advanced,  the  skin  lesions  are  accompanied  bj^ 
anaemia,  emaciation,  and  a  general  debility  that  may  terminate  in  death. 
As  in  other  parasitic  skin  diseases,  vigorous  animals  in  good  condition 
are  more  resistant  and  are  more  easily  cured  than  those  unthrifty  or  old 
and  emaciated. 

Transmission. — The  transmission  of  mange  from  horse  to  horse  or 
to  asses  and  mules  takes  place  by  contact  of  individuals  and  by  numerous 
ways  in  which  the  parasite  can  be  transported,  as  by  litter,  grooming 
utensils,  harness,  clothing,  or  any  object  upon  which  the  affected  animal 
has  rubbed.  Its  contagion  is  modified  considerably  in  relation  to  the 
stage  of  the  disease.  Early  in  its  course  the  acari  have  little  tendenc}^ 
to  leave  their  host,  but  after  one  or  two  generations,  with  the  formation 
of  the  typical  skin  lesions,  they  emigrate  readily,  either  directly  or  in- 
directly, from  one  animal  to  another. 

Mange  of  the  horse  can  be  transmitted  to  man  and,  reciprocally, 
that  of  man  to  the  horse,  though  such  cases  are  rare.  In  either  event  the 
parasite  does  not  find  a  favorable  soil  for  its  multiplication,  and  the 
invasion  is  but  transient,  such  affection  as  it  produces  usually  yielding 
promptly  to  treatment  or  spontaneously  disappearing  in  a  few  weeks. 
It  is  doubtful  whether  this  mange  can  be  commimicated  to  other  animals; 


108  PARASITES  OF  THE  DOMESTIC  ANIMALS 

varieties  of  the  sarcopt  accidentally  conveyed  from  their  natural  to  a 
foreign  species  of  host  meet  with  an  unfavorable  habitat  and,  if  cutaneous 
manifestations  follow,  it  may  be  assumed  that  they  must  in  any  case  be 
slight  and  of  relatively  short  duration. 

Psoroptic  Scabies  of  the  Horse. — Psoroptic  scabies  generally  appears 
about  the  regions  of  the  longest  hair,  as  at  the  base  of  the  forelock,  mane, 
and  tail.  It  at  once  gives  rise  to  pruritus,  which  is  accompanied  by 
rubbing  and  matting  of  the  hairs  as  in  mange,  with  which  form  it  is 
somewhat  similar  as  to  its  course  and  alterations.  It  spreads  much 
more  slowly,  however,  and  rarely  involves  the  whole  surface  of  the 
body. 

The  psoropt  does  not  burrow  beneath  the  skin's  surface  as  does  the 
sarcopt,  therefore  it  can  be  more  easily  found.  The  methods  recom- 
mended for  securing  the  Sarcoptes  will  apply  to  the  Psoroptes  as  well, 
though  to  obtain  the  latter  it  is  not  necessary  to  go  quite  as  deeply  for 
the  material.  In  this  connection  it  should  be  borne  in  mind  that  two 
or  all  three  forms  of  scabies  may  coexist  on  the  horse.  It  is  advisable, 
therefore,  in  certain  cases  to  look  for  the  mite  in  material  obtained  from 
various  affected  regions  of  the  body,  as  from  the  base  of  the  mane,  fore- 
lock, or  tail,  from  the  cheeks  and  breast,  and  from  the  lower  parts  of  the 
legs. 

Lesions. — While  the  local  alterations  in  psoroptic  scabies  are  severe, 
the  pruritus  intense,  and  the  scabs  generally  thicker  than  in  the  sarcop- 
tic  form,  it  is  a  less  serious  affection  in  that  the  mites  do  not  burrow, 
and  the  lesions  remain  much  longer  localized.  More  easily  and  promptly 
cured,  it  is  not  so  frequently  epizootic,  and  it  is  not  as  likely  to  spread  to 
other  horses  upon  the  same  premises. 

Transmission. — As  to  its  transmissibility  from  the  equine  species  to 
other  animals,  what  has  been  said  relative  to  this  of  the  Sarcoptes 
applies  also  to  the  Psoroptes. 

Chorioptic  Scabies  of  the  Horse. — This  form  of  scabies  begins  on 
the  extremities,  most  often  the  hind  feet  about  the  fetlocks  and  pasterns. 
From  here  it  spreads  to  the  hocks,  or  to  the  knees  if  from  the  fore  feet, 
sometimes  extending  further,  but  rarely  as  far  as  the  bod}^  Like  the 
psoroptes,  these  mites  seek  the  parts  covered  by  long  hair,  therefore 
horses  with  long  fetlocks  are  predisposed  to  attack. 

Symptoms. — The  first  symptom  of  the  invasion  is  itching,  which 
the  hoi'se  manifests  by  stamping,  kicking  the  side  of  the  stall,  efforts  to 
bite  the  legs,  or  rubbing  them  one  against  the  other.  This  irritation 
is  especially  noticeable  upon  the  animal's  return  from  work  and  at  night 
in  a  warm  stable.  Its  true  caiise  is  frequently  overlooked  in  considering 
it  a  vicious  habit. 

Chorioptic  scabies  is  slow  in  development,  and  is  most  troublesome  in 
winter.    This  is  probably  due  to  the  fact  that  the  feet  of  horses  at  this 


THE  MITES 


109 


time  of  the  year  are  more  exposed  to  mud  and  slush,  bringing  about  a 
macerated  and  inflammator}^  condition  of  the  skin  that  favors  the 
multipHcation  of  the  mites. 

Lesions. — Shortly  after  the  invasion  an  abundant  epidermic  des- 
quamation is  noticed  among  the  hairs  and  over  the  skin.  Tufts  of 
hair  are  easily  pulled  out,  and  patches  appear  where  the  skin  is  bare  and 
smooth.  Later  crusts  form  over  a  thickened  and  exudmg  skin,  which 
in  the  hollow  of  the  pastern  becomes  fissured  and  bleeding. 

Diagnosis. — In  view  of  the  special  seat  of  chorioptic  scabies,  other 
parts  not  bemg  involved,  it  is  scarcely  nec- 
essary to  confirm  its  differentiation  from 
other  forms  by  the  recovery  of  the  mite.  It 
is  important,  however,  to  know  whether 
the  case  is  truly  one  of  scabies,  and  this 
diagnosis  can  only  be  established  with  cer- 
tainty by  findmg  the  parasite.  If  present 
it  will  be  easih'  found  among  the  deeper 
parts  of  the  crusts  and  epidermic  scales. 

Prognosis  and  Transmission.  —  Foot 
scab  is  less  infectious  and  is  accompanied 
by  less  itching  than  the  other  forms.  The 
prognosis  is  also  more  favorable,  since,  ex- 
ceptmg  in  rare  cases,  the  disease  is  confined 
to  the  lower  parts  of  the  legs  and  usually 
to  the  hind  legs  onl}'.  Again,  unlike  other 
scabies,  it  has  little  if  any  general  effect 
upon  the  animal.  It  yields  readily  to  suit- 
able treatment,  and  it  is  not  hkely  that 
horses  recei\'ing  proper  care  as  to  cleanli- 
ness of  the  hair  and  skin  will  be  attacked, 
even  though  exposed  to  the  infection.  Its 
transmission  from  animal  to  animal  in  the 
same  stable  is  usually  bv  bedding  and 
grooming  utensils  in  the  hands  of  careless 
attendants. 


Fig.  67. — Chorioptes  communis 
var.  equi,  female;  ventral  view. 


Scabies  of  the  Sheep 


Sheep  may  be  affected  with  the  following  forms  of  scabies,  the  first 
mentioned  being  by  far  the  most  important  in  this  animal : 

1.  Psoroptic  scabies,  due  to  Psoroptes  communis,  var.  ovis. 

2.  Sarcoptic  mange,  due  to  Sarcoptes  scabiei,  var.  ovis. 

3.  Chorioptic  scabies,  due  to  Chorioptes  communis,  var.  ovis. 

4.  Folhcular  mange  due  to  Demodex  follicidorum,  var.  ovis. 
Psoroptic   Scabies   of   Sheep. — Through   its   exten.sive   prevalence 


no  PARASITES  OF  THE  DOMESTIC  ANIMALS 

among  sheep,  psoroptic  scabies  may  be  regarded,  from  an  economic 
standpoint,  as  the  most  important  of  all  scabies  affecting  live  stock. 
That  the  disease  has  been  known  for  many  centuries  is  evident  through 
references  to  it  in  early  writings,  including  the  Bible.  The  relationship 
of  the  mite  to  the  disease,  however,  was  not  determined  with  certainty 
until  the  nineteenth  century,  during  the  first  half  of  which  the  complete 
life  cycle  of  the  parasite  was  demonstrated.  It  was  shown  that  mites, 
like  larger  animals^  are  the  offspring  of  ancestors  and  are  not  of  sponta- 
neous origin  or  accidental  occurrence.  It  was  further  proven  by  animal 
experimentation  that  the  mites  were  not  present  as  a  result  of  the  scab, 
as  had  been  supposed  by  some,  but  that  the  scab  resulted  from  the 
presence  of  the  mites  and  could  be  produced  in  no  other  way. 

The  psoropt  of  sheep  scab  (Figs.  68  and  69)  lives  upon  the  surface  of 
the  body  where  it  is  most  thickly  covered  with  wool,  as  the  back,  sides, 
and  shoulders.  From  their  seat  of  invasion  the  colonies  will  spread  and 
these  areas  may  coalesce,  involving  large  patches,  though  the  regions  of 
short  wool,  as  the  belly  and  front  of  the  chest,  are  rarely  attacked. 

Symptoms  and  Lesions. — The  first  indications  of  the  disease  are 
rubbing  and  gnawing  at  the  wool  and  general  unrest  caused  by  the  itch- 
ing. As  the  changes  in  the  skin  progress  loosened  tufts  become  raised 
over  the  surface  of  the  fleece.  These  tags  are  soon  rubbed  or  pulled 
away  by  the  sheep,  and  the  fleece  over  the  affected  parts  becomes  ragged 
and  matted,  the  skin  finally  becoming  more  or  less  bare  and  showing 
at  this  stage  a  thickened,  furrowed,  and  bleeding  condition. 

If  the  skin  is  examined  before  the  shedding  of  the  wool  there  will  be 
seen  small  yellowish  nodules  and  papular  elevations  of  the  epidermis. 
The  latter  with  their  serous  exudate  dry  up,  forming  an  accumulation 
of  fatty  yellowish  scales  upon  the  skin  and  among  the  deeper  parts  of 
the  hairs.  The  papules  are  closer  together  as  the  punctures  of  the  psoropt 
become  more  numerous.  As  they  become  confluent  the  skin  thickens, 
and  the  drying  exudate  and  papular  debris  form  a  massive  yellowish 
crust.  This,  as  it  increases  layer  by  layer,  envelopes  and  mats  the 
wool,  lifting  the  fibers  from  their  follicles  and  raising  large  bunches 
above  the  surface  of  the  fleece.  These  detached  patches  will  soon  fall 
away,  the  denuded  skin  showing  a  variation  of  lesions  common  to 
scabies.  It  will  be  thickened,  cracked,  and  scabby,  and  there  may  be 
here  and  there  excoriations,  with  perhaps  sloughing  and  ulcerated  areas. 
The  acari  forsake  the  more  central  and  older  lesions  for  the  periphery 
of  the  denuded  patch  where  they  may  be  found  in  large  numbers  at 
the  roots  of  the  incrusted  wool  which  in  its  turn  will  fall  away.  Due  to 
direct  exposure  to  the  atmosphere,  old  denuded  or  sheared  areas  dry 
out  and  become  uniformly  covered  with  a  dry  parchment-like  crust 
beneath  which  the  skin  is  thickened  and  fissured. 

Course  and  Prognosis. — The  course  and  termination  of  the  disease 


THE  :mites 


111 


will  be  influenced  by  age,  condition,  character  of  fleece,  and  the  con- 
ditions under  which  the  sheep  are  kept.    Animals  debilitated  from  age, 


Fig.   68.— PsoroiJt 
(right)  surface. 


fpmalo;  dorsal  (left)  and  ventral 


or  other  cause,  offer  little  resistance,  while  lambs,  due  to  the  tenderness 
of  their  skin  and  their  dense  fleece,  are  apt  to  be  attacked  more  severely. 
Sheep  with  a  close  wool,  as  the  pure  or  grade  merino,  afford  an  ideal 
habitation  for  the  rapid  multiplication  of  the  parasites.    The  contagion 


Fig.  69. — Psoroptes  communis  var.   ovis,   male;  dorsal   (left)   and 
ventral  (right)  surface. 

of  any  form  of  acariases  in  sheep  is  facilitated  by  their  habit  of  living 
in  flocks.  The  disease  is,  therefore,  much  more  serious  in  winter  when 
the  animals  are  huddled  together,  especially  making  rapid  progress  if 


112  PARASITES  OF  THE  DOMESTIC  ANIMALS 

the  quarters  in  which  they  are  collected  are  damp  and  hot.  In  summer, 
after  shearing  and  turning  upon  pasture,  it  rapidly  subsides,  in  some 
cases  even  seeming  to  disappear. 

Psoroptic  scabies  in  sheep,  if  unchecked,  will  have  a  fatal  termination. 
Death  is  preceded  by  denudation  of  the  greater  part  of  the  body,  emacia- 
tion, anaemia,  and  a  progressive  weakness.  The  course  is  often  rapid 
in  stabled  sheep  and  those  predisposed;  within  one  or  two  months  it 
may  have  spread  over  the  greater  part  of  the  body,  while,  on  the  other 
hand,  the  disease  may  last  in  a  more  or  less  severe  form  for  a  year  or 
more. 

Transmission. — Sheep  scab  cannot  be  transmitted  to  other  animals, 
nor  can  psoroptic  scabies  of  other  animals  be  transmitted  to  sheep. 

Sarcoptic  Mange  of  Sheep. — Sheep  are  rarely  affected  with  this 
form.  When  it  occurs  it  can  at  once  be  distinguished  from  psoroptic 
scab  by  its  location,  which  is  exclusively  upon  parts  of  the  body  covered 
with  short  hair.  It  usually  has  its  beginning  about  the  upper  lip  or 
nostrils,  extending  from  here  to  other  parts  of  the  face  and  to  the  eye- 
lids and  ears.  In  cases  of  long  standing  it  may  spread  to  the  belly  and 
inner  sides  of  the  front  and  hind  legs. 

Prognosis. — The  course  of  the  disease  with  its  typical  skin  altera- 
tions has  already  been  described  under  Sarcoptic  Mange  of  the  horse. 
It  is  much  less  serious  in  sheep  than  in  the  horse,  however,  and  if  taken 
before  it  has  spread  extensively,  yields  easily  to  treatment. 

Transmission. — Sheep  and  goats  transmit  sarcoptic  mange  recipro- 
cally. It  has  been  reported  as  having  been  conveyed  from  these  animals 
to  man,  but  such  cases,  if  ever  occurring  authentically,  should  be  ex- 
tremely rare. 

Chorioptic  Scabies  of  Sheep. — As  in  the  horse,  chorioptic  scabies  of 
the  sheep  begins  in  the  hind  fetlocks  and  pasterns  where  it  is  charac- 
terized by  a  redness  of  the  skin  and  the  presence  of  fine  epidermic  scales. 
There  is  considerable  itching,  causing  the  animals  to  stamp  their  feet 
and  bite  at  the  infected  parts.  Later  yellowish  crusts  appear  which 
thicken,  and  the  skin  becomes  cracked  and  bleeding,  especially  about 
the  folds  of  the  pastern.  Only  rarely  does  the  affection  pass  to  the  fore 
legs  or  upward  to  the  udder  in  the  ewe,  or  to  the  scrotum  in  the  ram. 

Prognosis  and  Transmission. — Again,  as  in  the  horse,  the  Chorioptes 
are  not  inclined  to  migrate,  and  the  scabies  they  produce  is  but  sHghtly 
contagious.  It  yields  promptly  to  cleanliness  and  proper  treatment, 
subsiding  almost  entirely  when  the  flock  is  turned  upon  grass  in  the 
spring. 

Follicular  Mange  of  Sheep. — -The  follicular  mite  occasionally  in- 
vades the  eyelids  of  sheep.  Few  such  cases  have  been  recorded,  however, 
and,  in  this  country  at  least,  follicular  mange  is  of  little  importance  to 
flock  owners. 


THE  MITES  113 

Scabies  of  the  Goat 

Goats  may  l^e  affected  by  three  forms  of  scabies, — sarcoptic,  psoroptic, 
and  chorioptic.  The  first  mentioned  is  the  most  frequenth'  met  with  in 
these  animals,  having  its  seat,  as  in  sheep,  mainly  about  the  face.  The 
other  forms  are  rarely  met  with  in  goats.  Psoroptic  scabies  attacks  the 
external  ear,  forming  dark-colored,  fungus-Uke  scabs.  Chorioptic  scabies 
is  said  to  have  its  beginning  on  the  sides  of  the  neck  and  withers  and 
along  the  back. 

Scabies  of  Cattle 

Three  forms  of  scabies  affect  cattle.    These  are  as  follows: 

1.  Psoroptic  scabies,  due  to  Psoroptes  communis,  var.  botis. 

2.  Chorioptic  scabies,  due  to  Chorioptes  communis,  var.  boms. 

3.  Sarcoptic  mange,  due  to  Sarcoptes  scabiei,  var.  boiis. 

Scabies  is  less  frequent  in  cattle  than  in  horses  and  sheep,  in  North 
America  being  most  often  met  with  in  the  range  herds  of  the  West  and 
Northwest.  In  this  country  the  psoroptic  is  probably  the  most  fre- 
cjuent  form. 

Psoroptic  Scabies  of  Cattle. — This  usually  has  its  l)eginning  upon 
the  sides  of  the  neck  and  shoulders,  at  the  base  of  the  horns,  or  it  ma\' 
be  at  the  root  of  the  tail.  From  these  points  it  usually  advances  along 
the  back,  passing  to  the  sides,  and  in  severe  cases  eventually  involving 
the  greater  part  of  the  body.  In  its  s^^nptoms,  course,  and  skin  altera- 
tions it  is  in  all  essential  respects  analogous  to  the  same  form  of  scabies 
in  the  horse.  The  pruritus  is  intense,  the  animal  rubbing  and  scratching 
itself  in  every  way  possible,  often  causing  Ijloody  excoriations  of  the 
skin.  As  the  disease  advances  an  extreme  cachexia  sets  in,  and  the 
anaemic  and  much  weakened  animal  may  die  in  a  most  miserable  con- 
dition. 

Such  cases  are  most  likely  to  occur  al^out  the  close  of  the  winter 
months,  especially  in  cattle  stabled  or  herded  together  in  wami  quarters. 
While  upon  grass,  though  the  infection  may  remain,  its  symptoms  sub- 
side, and  in  the  falling  away  of  the  scabs  with  renewal  of  the  coat,  may 
even  seem  to  have  entirely  disappeared. 

Calves,  yearlings,  and  two-year-olds  suffer  most,  and  it  is  among 
these  that  there  is  more  likely  to  be  a  fatal  termination. 

Chorioptic  Scabies  of  Cattle, — This  form  in  cattle  is  commonh- 
known  as  tail  mange.  It  generally  appears  in  the  depressions  at  the 
base  of  the  tail  where  as  a  rule  it  remains  localized.  If  neglected  it  may 
spread  to  the  loins,  perineum,  and  inner  surface  of  the  thighs,  or  even 
over  a  considerable  surface  of  the  body,  though  such  cases  are  rare.  It 
is  exceptional  for  mange  to  appear  in  the  feet  of  cattle. 

Its  course  is  the  usual  one  of  chorioptic  scabies.    The  itching  is  mod- 


114  PARASITES  OF  THE  DOMESTIC  ANIMALS 

erate,  and  the  skin  becomes  covered  with  fine,  dry  scales,  later  becoming 
denuded,  fissured,  and  scabby. 

It  is  but  slightly  contagious  and,  except  in  cases  of  extreme  neglect, 
has  little  tendency  to  spread  upon  the  body.  Where  it  seems  to  progress 
beyond  the  limits  usual  to  the  choriopt,  it  should  be  determined  whether 
or  not  psoroptic  scabies  is  coexisting  with  it — a  condition  which  is 
quite  possible.  If  this  is  suspected,  material  from  several  affected 
locations  should  be  examined  for  recognition  of  the  infecting  species. 

Sarcoptic  Mange  of  Cattle. — Mange  of  the  ox  due  to  Sarcoptes  need 
be  no  more  than  mentioned  here.  Probably  in  every  case  where  it  has 
occurred  it  has  been  by  transmission  from  animals  more  likely  to  har- 
bor this  species,  as  the  horse  or  goat.  In  bovine  animals  the  disease  is 
usually  of  short  duration,  showing  less  tendency  to  spread  and  yielding 
more  promptly  to  treatment  than  in  the  horse.  It  affects  chiefly  the 
skin  about  the  eyes  and  cheeks  and  may  extend  to  the  sides  of  the 
neck. 

Mange  of  the  Hog 

Two  kinds  of  mange  affect  the  hog.    These  are  as  follows : 

1.  Sarcoptic  mange,  due  to  Sarcoptes  scabiei  var.  suis. 

2.  Follicular  mange,  due  to  Demodex  folliculorum  var.  suis. 
Sarcoptic  Mange  of  the  Hog. — Sarcoptic  mange  is  considered  to  be 

the  most  common  form  in  these  animals.  The  infecting  sarcopt  is  the 
largest  variety  of  the  species  and  may  be  seen  with  the  unaided  eye  as  a 
minute  moving  speck  among  the  removed  cutaneous  debris. 

Symptoms. — The  presence  of  the  disease  is  first  shown  upon  the 
skin  about  the  eyes  and  ears,  from  which  points  it  spreads  to  the  back 
of  the  neck,  withers,  shoulders,  and  back,  later,  if  unchecked,  invading 
the  greater  surface  of  the  body.  The  pruritus  is  extremely  severe  and  is 
especially  aggravated  in  animals  subjected  to  the  body  heat  of  crowded 
pens.  With  the  extension  of  the  itching  nodules  the  bristles  fall  out, 
and  the  skin  becomes  wrinkled  and  covered  with  brownish  or  dark 
gray  crusts.  Within  the  folds  the  skin  presents  the  morbid  changes 
usual  to  sarcoptic  mange;  it  is  fissured  and  bleeding  and  there  may  be 
ulcerations. 

Young  pigs  and  those  with  a  thick  curly  growth  of  hair  suffer  the 
most.  The  condition  j-etards  development  and  fattening,  and  severe 
cases  may  lead  to  general  debility  and  death. 

Transmission. — Contagion  is  by  contact  of  the  animals  with  each 
other,  essentially  facilitated  when  crowded  together  in  pens  or  lots. 
Because  of  the  habit  these  animals  have  of  rubbing  their  bodies,  ob- 
jects upon  which  infected  hogs  have  scratched  are  especially  a  source  of 
transmission. 

This  mange  of  the  hog  may  be  transmitted  to  man  and  to  the  dog  and 


THE  MITES  115 

possibly  also  to  the  horse,  but  the  eruption  produced  iu  such  cases  dis- 
appears spontaneously  in  a  few  days. 

Follicular  Mange  of  the  Hog. — Demodex  being  more  difficult  to 
recognize,  its  j^resence  in  the  skin  of  pigs  probably  occurs  more  often 
than  is  generally  supposed.  The  skin  alterations  which  the  follicular 
mites  bring  about  in  these  animals  is  comparativeh'  slight  and,  as  a  rule, 
are  not  such  as  to  perceptibly  interfere  with  general  health  or  growth. 
The  primary  seat  of  invasion  is  usually  the  skin  about  the  snout.  The 
lesions  may  extend  to  the  cheeks  and  even  to  the  neck  and  chest,  though 
such  spreading  of  follicular  mange  in  the  pig  is  not  often  observed. 

Maxge  of  the  Dog 

There  are  three  forms  of  canine  mange,  as  follows: 

1.  Sarcoptic  mange,  due  to  Sarcoptes  scahiei  var.  canis. 

2.  Follicular  mange,  due  to  Demodex  folliculorum  var.  canis. 

3.  Auricular  mange,  due  to  Otodectes  cynotis. 

Sarcoptic  Mange  of  the  Dog. — Sarcoptic  is  considered  the  most 
conmion  mange  affecting  the  dog.  Though  it  may  first  appear  upon 
any  part  of  the  body,  it  generally  begins  about  the  nmzzle,  especially 
upon  the  bridge  of  the  nose  or,  not  infrequently,  around  the  eyes,  at  the 
base  of  the  ears,  or  upon  the  breast.  As  it  spreads  the  ventral  surface, 
axilla,  and  thighs  become  involved,  the  morbid  process  extending  with 
such  rapidity  that  by  the  end  of  a  month  it  may  cover  the  greater  part 
of  the  body. 

Symptoms,  Course,  and  Lesions. — In  its  symptoms,  course,  and 
alterations  sarcoptic  mange  of  the  dog  is  shnilar  to  that  of  the  horse. 
It  is  first  manifested  upon  thin  and  unpigmented  skin  by  little  red  points 
which  are  soon  converted  into  papules.  These  rapidly  increase  in  num- 
ber and,  as  they  rupture  and  exude  their  serous  contents,  deposit  a 
scaly  accumulation  upon  the  skin  followed  by  the  formation  of  yellowish 
gray  crusts.  As  the  disease  progresses  the  denuded  skin  becomes 
thickened,  wrinkled,  and  excoriated,  the  cheeks,  neck,  and  breast 
especially  exhibiting  deep  folds.  The  itching,  always  intense,  is  much 
aggravated  by  an  increase  in  the  ])ody  tempei-ature,  as  may  be  brought 
about  b}'  running  or  warm  quarters. 

Where  large  areas  of  the  body  are  involved  in  the  disease,  emaciation 
and  genei-al  debility  set  in,  the  animal  at  times  giving  off  an  offensive, 
mouse-like  odor.  Finally,  if  the  animal  is  neglected  or  treatment  is 
unsuccessful,  death  will  ensue  by  the  end  of  two  or  three  months  from 
the  beginning  of  the  invasion. 

Transmission. — The  facts  of  contagion  pertaining  to  sarcoptic  mange 
of  other  animals  apply  to  this  disease  of  the  dog  as  well.  Young  dogs 
and  those  debilitated  are  predisposed  to  infection,  though  dogs  of  any 
age  or  condition  will  supj^ort  the  sarcopt  and  readily  develop  the  disease. 


116 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Follicular  Mange  of  the  Dog. — Demodectio  mange,  or  the  so-called 
red  mange  of  dogs,  is  of  frequent  and  world-wide  occurrence.  The 
lanciform  mites  enter  the  orifice  of  the  hair  follicle  where  they  multiply 
and  occupy  the  follicle  and  sebaceous  gland  in  large  numbers,  lying 
closely  pressed  together  and  almost  invariably  with  the  mouth  parts 
directed  toward  the  bottom  of  the  folHcle  (Fig.  70).  In  this  location 
they  may  be  found  in  all  stages  of  development,  from  eggs  to  sexually 
mature  individuals  and  ovigerous  females.  As  a  result  of  this  con- 
stant increase  there  is  a  dilation  of  the  hair  follicle  and  gland,  the  pres- 
sure and  irritation  producing  degenerative 
changes  in  the  lining  epithelium  of  the 
follicle  and  hair  papilla  which  causes  the 
hair  bulb  to  become  loosened  from  its 
attachment. 

Symptoms  and  Course. — The  degree  of 
irritation  and  extension  of  the  -inflamma- 
tory process  to  the  surrounding  tissue  will 
be  influenced  by  the  number  and  activity 
of  the  mites.  There  may  be  no  more  man- 
ifestation of  their  presence  than  a  hyper- 
secretion of  sebaceous  material.  Where,  on 
the  other  hand,  these  causative  factors  are 
sufficient  to  produce  an  acute  inflammation 
involving  the  surrounding  derma,  there 
will  be  a  dilation  of  the  contained  blood 
vessels  with  increased  formation  of  epi- 
dermic cells.  Increased  desquamation  of 
the  surface  cells  follows,  and  later  there  is 
an  invasion  of  pyogenic  organisms  into  the 
inflamed  and  dilated  follicles,  resulting  in 
the  formation  of  pustules  and  in  some  cases  large  abscesses. 

Though  follicular  mange,  owing  to  its  resistance  to  treatment  and 
general  septic  intoxication,  frequently  terminates  in  death,  its  course 
at  the  commencement  is  very  slow.  In  its  early  manifestations  there  are 
merely  somewhat  reddened  areas,  usually  of  the  skin  about  the  eyes, 
breast,  elbows,  or  it  may  be  at  the  toes.  As  the  hairs  fall  away  small 
papules  are  observed,  and  the  affected  patches  become  covered  with 
fine,  powder-like  scales.  The  infection  is  extended  by  the  mites  aban- 
doning the  originally  invaded  follicles  and  entering  the  surrounding 
healthy  ones,  the  spreading  being  aided  somewhat  by  the  rubbing  and 
licking  of  the  animal.  As  new  parts  are  invaded  the  skin  becomes  de- 
cidedly red  and,  especially  about  the  cheeks  and  breast,  thickened, 
wrinkled,  and  crusty;  the  eyelids  are  swollen  and  covered  at  their  borders 
by  a  purulent  discharge. 


m 


Fig.  70. — Demodex  folliculo- 
rum:  a,  mite  greatly  enlarged;  b, 
mites  in  hair  follicle  and  seba- 
ceous gland — enlarged  (after  Os- 
born,  from  Murry,  Bui.  No.  5, 
Bureau  of  Entomology,  U.  S. 
Dept.  of  Agr.). 


THE  MITES  117 

The  disease  finally  becomes  generalized,  the  skin  everywhere  ex- 
hibiting the  lesions  in  their  various  stages,  and,  with  it  all,  exhaling  a 
disgusting  odor.  The  pruritus  increases,  though  it  remains  somewhat 
intermittent,  and  at  no  time  is  as  severe  as  in  sarcoptic  mange.  With 
the  generalization  of  the  malady  its  effect  upon  the  whole  animal  or- 
ganism is  well  estal)lished.  The  appetite  is  lost  and  emaciation  ad- 
vances, the  subsequent  marasmus  leading  to  a  fatal  termination. 

Transmission. — Due  to  the  intra-cutaneous  location  of  the  parasites, 
follicular  mange  is  not  as  contagious  as  other  forms;  furthermore  a  pre- 
disposition is  necessary  for  its  development,  and  this  is  fomid  in  young 
and  short-haired  animals.  Adult  dogs  with  healthy  skins  are  rarely 
attacked. 

Whether  the  dermatitis  in  follicular  mange  is  primarily  due  to  the 
presence  of  the  Demodex  may  be  questioned.  The  assumption  that  this 
mite  is  present  in  the  hair  follicles  of  all  dogs  needs  the  support  of 
further  investigation.  Accepting  it  from  clinical  observation  as  a  proba- 
bility— and  with  the  predisposing  factors  of  other  forms  of  acariasis  in 
mind — there  seems  good  reason  to  suppose  that  the  mites,  living,  we 
may  say,  as  commensals,  find  in  erythematous  and  eczematous  skins 
surroundings  favoring  their  nutrition  and  more  rapid  multiplication, 
thus  bringing  about  the  secondary  severe  dermatitis  of  follicular  mange, 
the  pyodermatitis  resulting  from  subsequent  intra-follicular  invasion 
by  pyogenic  organisms. 

Auricular  Mange  of  the  Dog. — Otacariasis  is  of  comparatively  fre- 
quent occurrence  in  dogs,  by  reason  of  its  contagiousness,  being  most 
often  met  with  in  hounds  kept  in  packs.  Symptoms  of  the  presence  of 
the  mites  are  frequent  scratching  and  flapping  of  the  ears,  which  may 
be  accompanied  by  whining  and  howling.  Epileptiform  seizures  are 
not  infrequently  an  accompaniment,  these  especially  likelj'  to  occur 
when  the  animal  is  running.  On  examination  the  auditory  canal  is 
found  to  contain  an  adherent,  soot-colored  powder  and  a  fetid  wax 
which  may  be  in  sufficient  abundance  to  produce  deafness  by  obstruc- 
tion of  the  canal  and  pressure  upon  the  t^nnpanum.  An  examination  of 
this  material  mider  magnification  will  reveal  the  Otodectes  in  large 
numbers. 

Prognosis. — Otacariasis  yields  readily  to  treatment,  but  if  neglected 
may  have  serious  consequences.  The  animal  may  die  during  an  attack 
of  con\'T.i]sions  or,  if  it  survive,  be  rendered  useless  as  a  hunter. 

Mange  of  the  Cat 

The  cat  may  be  affected  with  the  two  following  forms  of  mange : 

1.  Notoedric  mange,  due  to  Notoedres  cati  var.  cali. 

2.  Auricular  mange,  due  to  Otodectes  cynotis. 


118 


PARASITES  OF  THE  DOMESTIC  ANI]\L\LS 


Notoedres  cati,  var.  cati  (Sarcoptes  minor  var.   cati,   Fig.  71),  the 

dwarf  sarcopt,  is  a  small  species  having  the  body  nearly  spherical.    The 

dorsal  folds  of  the  integument  are  circular.    The  anus  is  dorsal.    There 

are  six  anterior  dorsal  spinules  and  but  twelve 

^ r 1     posterior.     The  arrangement    of  the   stalked 

u  \       j^  suckers  is  the  same  as  in  Sarcoptes  scabiei. 

^  «|b^^  A<^  Course  and  Diagnosis. — Notoedric  mange 

/^d^^^Hkfi^         of  the  cat  usuall}^  begins  about  the  ears  and 

^^^^^^^^^  upper   part  of  the  neck,   extending  over  the 

^^^^^^^^H         forehead  and  then  over  the  head  generally. 

^^^^^^^^H         As  a  rule  it  remains  limited  to  these  regions, 

^^^^^^^^^V"^     rarely  passing  to  the  body.    The  disease  fol- 

y^^^H^^^^         lows  the  usual  course  and  alterations  of  sar- 

f^^Ktl^^    \       Coptic  mange,  the  cat  giving  evidence  of  the 

I       /  \        \      intense  itching  by  frequently  shaking  the  head 

/  \        \      and   wiping  it  with  its  paws.     In  neglected 

I    cases  animals  may  become  much  emaciated 

Fig.  71.— Genus  Notoedres.    and  may  die  in  a  few  months. 

Due  to  the  wrinkled,  papular,  and  crusty 
skin  and  its  persistency  of  location  upon  the  head,  the  diagnosis  of 
this  mange  on  the  cat  is  not  difficult.  Its  differentiation  from  other 
itching  skm  diseases  may  be  made  certam  by  the  discovery  of  the  para- 
site, which  is  readily  obtained  in 
material  scraped  from  beneath  the 
crusts. 

Auricular  Mange  of  the  Cat. — 
Auricular  mange  seldom  occurs  in 
the  cat.  It  is  caused  by  the  same 
species  of  mite  causing  auricular 
mange  of  the  dog  and  is  similar  in 
its  symptoms  and  course. 

Scabies  of  the  Rabbit 

Two  species  of  scab  mites  afflict 

the  rabbit, — Notoedres  cati  var.  cuni-  fig.  72.— Psoroptes    communis    var. 

■culi  and  Psoroptes   communis   var.  cunicuii     (from     photomicrograph     of 

.CUnicidi    (Fig.  72),    the    latter    CaUS-     counted  specimen,  by  Hoedt). 

ing  auricular  scabies  or  psoroptic  otacariasis. 

In  the  rabbit  notoedric  mange  most  often  has  its  beginning  about  the 
nose,  from  which  it  extends  to  the  upper  part  and  sides  of  the  head  where 
it  remains  localized.  Its  location,  symptoms,  and  course  are  similar  to 
those  of  the  same  form  of  mange  in  the  cat. 

Auricular  scabies  of  the  rabbit  commences  deep  in  the  concha,  grad- 
ualty  involving  the  skin  of  the  entire  inner  side.     Its  presence  is  first 


THE  MITES  119 

indicated  by  the  pruritus  which  the  animal  indicates  by  tossing  its  head 
and  scratching  the  ears  with  the  hind  feet.  If  the  deeper  parts  of  the 
ear  are  examined  early  in  thfe  disease  there  will  be  found  a  yellowish, 
fetid  matter  in  which  many  of  the  mites  may  be  seen  with  the  aid  of  a 
hand  lens.  At  the  end  of  a  few  months  the  greater  part  of  the  inner 
side  of  the  ear  becomes  covered  with  a  thick  layer  of  scabs  in  which  the 
Psoroptes  are  literally  swarming.  Usually  they  remain  localized  to  the 
ear,  rarely  invading  surrounding  parts. 

In  prolonged  cases  of  auricular  scabies  rabbits  lose  their  appetites 
and  become  emaciated,  diarrhea  sets  in,  and  the  animals  finally  die  in 
an  advanced  state  of  cachexia. 


CHAPTER  XI 

TREATMENT  OF  MANGE  AND   SCABIES 

General  Considerations. — Methods  of  treatment  of  scabies  will  vary 
according  to  the  form  of  the  disease  to  be  dealt  with  and  also  according 
to  the  kind  and  number  of  animals  to  be  treated.  As  a  general  rule  the 
application  of  acaricides  should  be  preceded  by  clipping  the  hair  from 
either  a  part  or  the  whole  of  the  body,  dependmg  upon  whether  the 
affection  is  localized  or  general.  The  crusts  should  then  be  softened  and 
removed  by  washing  with  warm  soapsuds  and  a  stiff  brush,  after  which 
the  remedy  chosen  may  be  applied. 

The  whole  process  is  to  be  repeated  in  ten  to  fourteen  days  in  order  to 
destroy  mites  from  eggs  which  escaped  the  first  treatment.  It  is  im- 
portant that  there  should  be  clean  surroundings  and,  especially  where 
emaciation  is  an  accompaniment,  an  abundance  of  nutritious  food. 
Sarcoptic  mange  will  require  more  energetic  remedies  than  other 
forms  where  the  mites  live  upon  the  surface  and  among  the  crusts  of 
the  skin. 

Internal  medication  is  of  little  or  no  value.  A  cure  can  only  be  reached 
by  the  destruction  of  the  acari,  accomplished  by  the  local  application  of  a 
suitable  acaricide.  In  the  use  of  such  agents  their  irritant  or  possible 
toxic  effects  upon  the  animal  treated  are  to  be  borne  in  mmd.  To  avoid 
a  sudden  and  general  checking  of  the  cutaneous  functions,  oiatments 
and  oleaginous  materials  are  not  to  be  spread  over  the  entire  body  at 
one  application,  nor  should  the  body  be  dressed  over  more  than  one- 
fourth  to  one-half  of  its  area  with  preparations  containing  carbolic  acid, 
creosote,  cresol,  tobacco,  or  other  such  ingredients.  Those  containing 
mercury  or  arsenic,  in  addition  to  these  limitations,  should  never  be 
used  upon  animals  such  as  cattle,  dogs,  and  cats  as  these  animals  will 
lick  the  dressed  parts. 

Where  large  numbers  of  animals  are  affected  in  a  flock  or  herd,  in- 
dividual treatment  involvmg  clipping,  scrubbing,  and  the  application 
of  remedies  by  hand,  is  not  practicable.  In  such  cases  a  method  of 
dippmg  must  be  resorted  to.  It  is  essential  to  the  success  of  the  treat- 
ment that  thorough  disinfection  measures  be  applied  to  surroundings 
and  to  such  portable  paraphernalia  as  may  serve  as  a  means  of  reinfec- 
tion. In  this  connection  it  should  be  borne  in  mind  that  the  mites  may 
live  from  two  weeks  to  a  month  or  more  ofT  a  host,  the  longer  periods 
usually  amid  favorable  conditions,  such  as  warm  stables  and  blankets. 


TREATMENT  OF  MANGE  AND  SCABIES  121 

The  treatments  given  l^elow  deal  successiveh'  with  the  chfferent  forms 
of  the  disease  and  embody  such  modifications  as  may  be  required  for 
the  various  domestic  mammals. 

Treatment  of  Sarcoptic  ^Iaxge 

Treatment  of  Sarcoptic  Mange  of  the  Horse. — Affected  animals 
should  be  isolated  in  quarters  where  they  will  not  be  in  contact  with 
each  other.  Unless  the  disease  is  distinctly  localized  it  is  better  to  clip 
the  hair  from  the  entire  body;  its  removal  will  often  reveal  the  lesions 
over  areas  otherwise  unsuspected.  The  clipping  is  not  to  be  done  in 
the  stable  or  in  a  wind  that  will  scatter  the  hairs  about.  All  of  the 
hairs  should  be  carefully  collected  and  burned. 

The  next  procedure  is  the  removal  of  the  crusts  in  order  that  the 
remedy-  used  may  be  applied  directly  to  the  skin.  This  is  best  accom- 
plished by  the  use  of  soft  soap  well  rubbed  upon  the  scabby  surface.  A 
thick  lather  is  then  formed  by  the  application  of  a  limited  quantity  of 
warm  water.  This  should  be  well  worked  into  the  crusts  with  a  brush 
and  allowed  to  remain  for  an  hour.  The  softened  crusts  may  then  be 
removed  with  a  brush  or,  better,  a  wooden  scraper  and  warm  soapy 
water,  and  the  body  finally  rinsed  with  clear  tepid  water  applied  with  a 
sponge.  The  scraping  process  should  be  done  gently  and  in  a  manner 
that  will  add  as  little  irritation  as  possible  to  an  already  inflamed 
skin.  After  the  skin  has  Ijecome  perfectly  dry  it  is  ready  for  the  remedy 
which  is  to  be  applied  with  a  view  to  the  destruction  of  the  parasites. 

There  are  a  number  of  such  remedies  in  the  use  of  which  practitioners 
have  had  a  varied  experience.  Creosote  is  among  the  most  effectual. 
It  may  be  used  in  any  of  the  following  combinations:  (1)  Creosote  one 
part,  oil  sixteen  to  twenty  parts;  (2)  creosote  one  part,  oil  of  tar  and  soft 
soap  of  each  ten  parts;  (3)  creosote  five  parts,  alcohol  five  parts,  water 
twenty  parts.  With  either  of  these  not  more  than  half  of  the  body 
should  be  dressed  at  alternate  periods  of  six  days  until  the  entire  body 
has  had  two  or  three  applications.    It  should  be  applied  by  rubbing. 

Other  remedies  which  have  given  satisfactory  results  are:  (1)  Lime 
and  sulphur  dip  (Formula  No.  1,  page  125),  two  or  three  applications  at 
intervals  of  one  week;  (2)  creolin  and  soft  soap,  of  each  one  part,  alcohol 
eight  parts.  Rub  upon  one  side  of  the  body  on  alternate  days;  after  the 
body  has  had  three  applications  rest  three  days  and  repeat ;  (3)  decoction 
of  tobacco  five  per  cent.  Apply  over  one-fourth  to  one-third  of  the  body 
each  da^-;  repeat  three  or  four  times  at  intervals  of  one  week. 

Unctuous  and  oily  preparations  are  to  be  preferred  to  the  more  fluid 
ones  as  they  are  more  penetrating  and,  adhering  to  the  skin,  their  action 
is  prolonged.  For  this  reason  they  are  especially  better  suited  for  the 
treatment  of  sarcoptic  mange.     The  lime  and  sulphur  preparation  is, 


122  PARASITES  OF  THE  DOMESTIC  ANIMALS 

however,  much  used  and  is  said  to  give  excellent  results.  Cure  will 
not  be  complete  until  all  of  the  mites  have  been  destroyed.  Animals 
should  therefore  be  kept  under  careful  observation  for  some  time  after 
treatment  for  the  detection  of  suspicious  sjanptoms,  such  as  itching. 
Such  cases  may  be  checked  at  their  inception  by  less  drastic  measures 
than  at  first  employed.  Often  a  few  applications  of  mercurial  ointment, 
or  equal  parts  of  oil  and  oil  of  tar  containing  ten  per  cent,  of  carbolic 
acid,  rubbed  over  the  limited  area,  will  be  sufficient. 

To  prevent  the  reappearance  of  the  disease  it  is  obviously  essential 
that  harness,  clothing,  groommg  utensils,  and  all  other  articles  which 
may  act  as  vehicles  for  reinfection,  be  disinfected.  This  is  best  done 
with  boiling  water.  Articles  which  might  be  injured  by  this  treatment 
may  be  washed  with  a  strong  solution  (ten  per  cent.)  of  lysol  or  creolin. 

Treatment  for  mange  given  at  the  close  of  the  winter  months  should 
be  repeated  in  the  fall,  even  though  the  disease  has  been  apparently 
cured.  This  is  a  precautionary  measure  to  destroy  the  few  mites  which 
may  have  survived  upon  the  animal  during  the  summer,  and  which 
may  again  produce  the  disease  under  the  more  favorable  conditions  for 
their  reproduction  which  prevail  during  the  fall  and  winter  months. 

Treatment  of  Sarcoptic  Mange  of  the  Hog. — Where  but  few  animals 
are  to  be  treated  they  should  first  be  thoroughly  cleaned  by  scrubbing 
with  soap  and  warm  water  and  the  skin  rinsed  and  dried. 

The  following  ointments  have  been  recommended  for  application 
to  the  skin  after  it  has  been  thus  prepared:  (1)  Sublimed  sulphur  two 
parts,  potassium  carbonate  one  part,  lard  eight  parts  (Helmerich's 
pomade);  (2)  creosote  one  part,  lard  twenty-five  parts;  (3)  sulphur  ten 
parts,  lard  thirty  parts.  These  applications  are  to  be  repeated  three 
times  at  intervals  of  about  five  days. 

Such  methods,  however,  are  out  of  the  question  where  a  large  number 
of  animals  is  involved.  In  such  cases  dipping  in  a  liquid  preparation 
is  the  only  practical  form  of  treatment.  For  this  purpose  the  following 
lime  and  sulphur  formula  is  recommended  by  the  United  States  Bureau 
of  Animal  Industry: 

Flowers  of  sulphur 24  lbs. 

Unslaked  hme 10  lbs. 

Water 100  gals. 

Prepare  as  under  lime  and  sulphur  formulae  for  scab  in  sheep  (page 
125). 

The  hogs  should  be  kept  away  from  wallows  for  several  days  before 
and  after  dipping.  Each  animal  should  be  kept  in  the  dip  long  enough 
for  the  liquid  to  be  well  rubbed  into  the  skin  with  a  stiff  brush,  care  being 
taken  that  all  parts  of  the  body,  including  the  head  and  ears,  are  reached 
by  the  remedy.    Animals  should  not  be  dipped  in  cold  weather. 


TREATMENT  OF  MANGE  AND  SCABIES  123 

Essentially,  pens  and  yards  must  be  cleaned  up  and  all  litter  burned. 

Treatment  of  Sarcoptic  Mange  of  the  Dog. — Dogs  should  be  clipped 
and  the  skin  covered  with  a  thick  lather.  A  good  apphcation  for  this 
purpose  is  green  soap  dissolved  in  an  equal  quantity  of  alcohol.  Let 
this  remain  two  to  four  hours,  then  remove  the  crusts  with  a  brush  and 
warm  soapy  water.  Rinse  and  allow  the  skin  to  become  dry.  One  of 
the  following  remedies  may  then  be  applied:  (1)  Creosote  one  part,  oil 
fifteen  to  twenty  parts;  (2)  creosote  one  part,  green  soap  and  alcohol  of 
each  eight  parts;  (3)  subhmed  sulphur  two  parts,  potassium  carbonate 
one  part,  lard  eight  parts  (Helmerich's  pomade);  (4)  creolm  one  part, 
alcohol  fifteen  parts;  (5)  Peruvian  balsam  two  parts,  creolin  one  part, 
alcohol  twenty  parts;  (6)  naphthalin  two  parts,  vaseline  eight  parts, 
oil  of  th\ane  and  oil  of  lavender  of  each  one  part. 

The  last  named  mixture  is  soothmg  to  the  skin,  agreeable,  and  quite 
suitable  for  small  house  dogs.  It  is  not  to  be  depended  upon,  however, 
in  old  and  generalized  cases.  To  avoid  a  too  generally  irritant  or  toxic 
effect  the  acaricide  should  be  applied  to  not  more  than  one-fourth  to 
one-third  of  the  bodj^  each  da^^  It  should  be  applied  freely  and  energet- 
ically and  left  on  for  three  or  four  days.  It  may  then  be  washed  off 
with  tepid  soapy  water.  At  the  end  of  three  or  four  days  the  application 
is  to  be  repeated  m  the  same  manner,  and  again  repeated  until  there  is 
no  further  itching  or  formation  of  scabs.  The  animal  should  be  pre- 
vented from  licking  by  fitting  it  with  a  broad  collar  or  by  binding  the 
mouth  with  tape. 

Preparations  of  tar  had  better  not  be  used  upon  dogs.  Remedies  con- 
taining carbolic  acid,  mercurj",  tobacco,  and  other  poisons  are  also  to  be 
avoided,  as  any  measure  adopted  to  prevent  licking  is  liable  to  be  de- 
feated by  the  dog  and  a  serious  poisoning  result. 

The  usual  precautions  as  to  cleaning  up  of  surroundings  should  of 
course  be  adopted  here. 

Treatment  of  Notoedric  Mange  of  the  Cat. — Cats  rebel  against  and 
actually  suffer  from  washmg,  therefore  treatment  of  these  animals  is 
limited  to  the  use  of  ointments.  The  hair  should  be  clipped  from  the 
affected  parts  and  a  small  amount  of  vaseline  applied  which  may  be 
removed  in  an  hour  or  two  by  rubbing  with  dry  bran  and  a  cloth,  re- 
moving in  this  operation  as  many  of  the  crusts  as  possible. 

The  acaricide  ointment  best  adapted  to  the  cat  is  that  of  Helmerich, 
consisting  of  sublimed  sulphur  two  parts,  potassium  carbonate  one  part, 
lard  eight  parts.  The  application  of  this  is  to  be  repeated  at  intervals 
of  four  to  six  days  until  scab  formation  and  itching  have  ceased.  It 
may  be  removed  by  rubbing  in  the  manner  already  stated.  Peruvian 
balsam  is  perhaps  more  effective,  but  in  cats  may  cause  severe  cerebral 
disturbance  followed  by  stupor  and  even  death.  If  used  at  all  it  should 
be  with  extreme  caution. 


124  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Due  to  the  usual  location  of  notoedric  mange  of  the  cat  upon  the 
head,  the  dressing  is  inaccessible  to  licking,  though  the  pads  of  the  feet 
are  likely  to  be  applied  to  it  and  afterward  licked.  It  is  scarcely  neces- 
sary to  say  that  preparations  containing  tobacco,  carbolic  acid,  and 
other  poisons  should  be  strictly  avoided  in  the  treatment  of  cats. 

Treatment  of  Notoedric  Mange  of  the  Rabbit. — Remove  the  hair 
from  the  affected  area  and  for  a  considerable  margin  around  it,  apply  a 
lather  of  soft  or  green  soap,  allow  to  remain  an  hour  or  two,  wash  off, 
and  repeat  as  necessary  to  remove  scabs.  When  the  parts  have  be- 
come dry,  treat  with  the  ointment  of  Helmerich  as  for  mange  of 
the  cat. 

Treatment  of  Sarcoptic  Mange  of  the  Goat. — Clip  the  hair  and 
prepare  the  parts  with  soapy  lather  as  directed  for  other  animals.  Treat 
with  a  sulphur  ointment  or  a  preparation  of  creosote,  as  creosote  one 
part,  oil  fifteen  parts.    Repeat  as  previously  directed. 

Owing  to  the  intractability  of  goats,  dipping  is  attended  with  difficul- 
ties and,  furthermore,  is  badly  borne  b}^  these  animals. 

Treatment  of  Sarcoptic  Mange  of  Sheep. — Remove  crusts  after 
softening  with  a  lather  of  soft  or  green  soap,  dry,  and  apply  (1)  creosote 
one  part,  oil  of  tar  and  soft  soap  of  each  twenty  parts;  (2)  sublimed  sul- 
phur one  part,  lard  four  parts,  or  (3)  the  ointment  of  Helmerich  may  be 
used.    Repeat  as  directed  for  other  animals. 

Treatment  of  Sarcoptic  Mange  of  Cattle. — After  clipping  and  prep- 
paration  of  the  skin  by  removal  of  the  crusts  as  has  been  repeatedly 
stated,  apply  the  lime  and  sulphur  mixture  as  given  and  prepared  under 
scab  of  sheep,  repeating  three  or  four  times  at  intervals  of  five  days. 
Good  results  may  also  be  obtained  by  the  use  of  sulphur  in  the  form  of 
an  ointment,  as  one  part  of  sulphur  to  four  parts  of  hog's  lard.  Prepara- 
tions containing  such  agents  as  creosote,  lysol,  or  creolin  are  best  limited 
to  cases  confined  to  the  head  and  upper  parts  of  the  neck,  regions  in- 
accessible to  the  tongue.  They  may  be  used  in  the  following  combina- 
tions: (1)  Creosote  one  part,  oil  fifteen  parts;  (2)  creosote  one  part, 
oil  of  tar  and  soft  soap  of  each  fifteen  to  twenty  parts;  (3)  creolin  and 
soft  soap  of  each  one  part,  alcohol  eight  parts;  (4)  lysol  in  five  per  cent, 
solution. 

All  of  these  are  to  be  washed  off  with  soapy  water  after  three  days 
and  the  treatment  repeated  as  necessary. 

Treatment  of  Psoroptic  Scabies 

Treatment  of  Psoroptic  Scabies  of  the  Sheep. — Proper  hygienic 
conditions  and  an  abundance  of  substantial  nourishment  will  do  much 
to  protect  sheep  from  the  contagion  of  scab,  but  where  it  has  made  its 
appearance  in  a  flock  such  measures  are  only  to  be  relied  upon  as  con- 


TREATMENT  OF  MANGE  AND  SCABIES  125 

tributing  to  a  rational  treatment  designed  to  rid  the  sheep  of  the  disease 
by  killing  the  parasites.  The  application  l)y  hand  of  either  ointments, 
fluid  preparations,  or  powders  for  this  purpose  is  practically  useless. 
The  acaricide  chosen  for  the  treatment  of  psoroptic  scabies  of  sheep 
should  be  applied  by  dipping.  It  is  better  not  to  consume  time,  energy, 
and  patience  upon  remedies  which  are  not  or  cannot  be  used  by  this 
method. 

Lime  and  Sulphur  Dip. — Many  formulae  for  dips  have  been  pub- 
lished, most  of  them  containing  lime,  sulphur,  tobacco,  or  arsenic  as 
their  base.  The  term  "lime-and-sulphur  dip"  does  not  refer  to  an 
exact  formula  but  includes  a  large  number  of  formulae  containing  the 
lime  and  sulphur  in  different  proportions.  While  the  ingrediants  of  a 
dip  should  be  in  such  proportion  as  to  make  it  a  reliable  parasiticide,  it 
is  essential  that  it  should  cause  little  or  no  harm  to  the  sheep  or  fleece. 
The  subject  of  dips  has  been  carefully  gone  into  by  the  United  States 
Bureau  of  Animal  Industry  and  the  conclusion  reached  that  probably 
the  most  effective  dips  are  those  containing  sulphur  and  tobacco,  and 
sulphur  and  lime  of  such  strength  that  they  are  not  injinious  to  the  sheep 
and  of  minimum  damage  to  the  fleece.  Among  the  formulse  for  lime  and 
sulphur  dips  mentioned  bv  the  Bureau  are  the  following  (Farmer's 
Bull.  No.  159) : 

No.  1 

Flowers  of  sulphur 24  lbs. 

Unslaked  lime 8  lbs. 

Water 100  gals.. 

No.  2 

Flowers  of  sulphur 33  lbs. 

Unslaked  lime 11  lbs. 

Water 100  gals. 

For  fresh  scab,  formula  No.  1  will  act  as  well  as  those  with  a  greater 
amount  of  lime.  In  old  cases  with  parchment-like  scab  a  stronger  dip, 
as  formula  No.  2,  is  to  be  preferred. 

The  following  method  of  preparing  the  mixture  is  recommended  l)y 
the  Bureau: 

"A.  Take  eight  to  eleven  pounds  of  unslaked  lime,  place  it  in  a  mortor 
box,  kettle,  or  pail  of  some  kind,  and  add  enough  water  to  slake  the  lime 
and  form  a  'lime  paste'  or  'lime  putty.' 

"Many  persons  prefer  to  slake  the  lime  to  a  powder,  which  is  to  l)e 
sifted  and  mixed  with  sifted  sulphur.  One  pint  of  water  will  slake  three 
pounds  of  lime,  if  the  slaking  is  performed  slowly  and  carefully.  As  a 
rule,  however,  it  is  necessary  to  use  more  water.  This  method  takes 
more  time  and  requires  more  work  than  the  one  given  above,  and  does 


126  PARASITES  OF  THE  DOMESTIC  ANIMALS 

not  give  any  better  results.  If  the  boiled  solution  is  allowed  to  settle,  the 
ooze  will  be  equally  as  safe. 

"B.  Sift  into  the  lime  paste  three  times  as  many  pounds  of  Flowers 
of  sulphur  as  used  of  lime,  and  stir  the  mixture  well. 

"Be  sure  to  weigh  both  the  lime  and  sulphur.  Do  not  trust  to  measur- 
ing them  in  a  bucket  or  guessing  at  the  weight. 

"C.  Place  the  sulphur-lime  paste  in  a  kettle  or  boiler  with  about 
twenty-five  to  thirty  gallons  of  boiling  water,  and  boil  the  mixture  for 
two  hours  at  least,  stirring  the  liquid  and  sediment.  The  boiling  should 
be  continued  until  the  sulphur  disappears,  or  almost  disappears,  from 
the  surface,  the  solution  is  then  of  a  chocolate  or  liver  color.  The  longer 
the  solution  boils  the  more  the  sulphur  is  dissolved,  and  the  less  caustic 
the  ooze  becomes.  Most  writers  advise  boiling  from  thirty  to  forty 
minutes,  but  the  Bureau  obtains  a  much  better  ooze  by  boiling  from 
two  to  three  hours,  adding  water  when  necessary. 

"D.  Pour  the  mixture  and  sediment  into  a  tub  or  barrel  placed 
near  the  dipping  vat  and  provided  with  a  bung  hole  about  four  inches 
from  the  bottom,  and  allow  ample  time  (two  to  three  hours,  or  more  if 
necessary)  to  settle. 

"The  use  of  some  sort  of  a  settling  tank  provided  with  a  bung  hole 
is  an  absolute  necessity,  unless  the  boiler  is  so  arranged  that  it  may  be 
used  both  for  boiling  and  settling.  An  ordinary  kerosene  oil  barrel 
will  answer  very  well  as  a  small  settling  tank.  .  To  insert  a  spigot  about 
three  to  four  inches  from  the  bottom  is  an  easy  matter.  Draining  off 
the  liquid  through  a  spigot  has  the  great  advantage  over  dipping  it  out, 
in  that  less  commotion  occurs  in  the  liquid,  which  therefore  remains 
freer  from  sediment. 

"E.  When  fully  settled,  draw  off  the  clear  liquid  into  the  dipping 
vat  and  add  enough  water  to  make  100  gallons.  The  sediment  in  the 
barrel  may  then  be  mixed  with  water  and  used  as  a  disinfectant,  but 
under  no  drcumstances  should  it  be  used  for  dipping  purposes." 

There  are  a  number  of  good  proprietary  dips  upon  the  market  which 
will  l)e  found  convenient  and  effectual.  No  dip  should  be  used,  however, 
unless  the  ingredients  and  their  exact  proportion  are  known  to  the  user. 
Secret  formulse  put  out  by  irresponsible  parties  should  be  avoided. 

Dipping  Vats. — Where  but  few  sheep  are  to  be  treated  the  dipping 
arrangements  may  be  quite  simple.  A  tub  or  trough  to  which  a  draining 
platform  is  attached  will  serve  the  purpose.  A  small  vat,  suitable  for 
dipping  small  flocks,  may  be  constructed  of  wood  or  concrete.  It  should 
be  about  nine  inches  wide  at  the  bottom,  four  feet  deep,  and  two  feet 
six  inches  wide  at  the  top.  Its  length  will  depend  upon  the  number  of 
sheep  to  be  treated.  A  convenient  length  is  nine  feet  at  the  top,  the 
floor  having  a  length  of  four  feet.  From  one  foot  above  one  end  of  the 
floor  an  incline  with  cross  cleats  rises  to  the  top  end  of  the  vat.    From 


TREATMENT  OF  MANGE  AND  SCABIES  127 

here  the  incHne  may  lead  to  a  drippmg  platform  which  maj'  easily  be 
improvised  for  the  purpose.  This  should  be  so  constructed  and  applied 
that  the  drip  will  flow  back  into  the  vat. 

Plans  for  more  elaborate  dipping  plants,  suitable  for  large  flocks,  may 
be  obtained  from  bulletins  issued  by  the  Bureau  of  Animal  Industr}', 
United  States  Department  of  Agriculture. 

To  obtain  the  best  results  sheep  should  be  sheared  before  dipping, 
and  the  dip  used  at  a  temperature  of  100°  to  110°  F.  Keep  each  sheep 
submerged  two  minutes  by  the  watch,  forcing  the  head  under  at  least 
once  just  before  the  animal  comes  out.     The  dips  should  be  freshly 


Fig.  73. — .\  small  portable  dipping  vat  for  .small  flock.s  (from  Bull.  No.  21, 
Bureau  of  .\n.  Ind.,  Dept.  of  Agr.). 

prepared  for  each  dipping;  if  permitted  to  stand  for  repeated  treatment 
failures  and  possibly  injurious  effects  may  result. 

Other  Dips. — Tobacco  dips,  used  either  with  or  without  sulphur, 
are  now  nnich  in  use  and  give  excellent  results.  Owing  to  the  poisonous 
character  of  nicotine,  the  active  principle  of  tobacco  upon  which  these 
dips  depend  for  their  action,  the  exact  nicotine  content  of  the  dip  should 
be  known  before  it  is  used.  This,  according  to  the  Bureau  of  Animal 
Industry,  should  not  exceed  0.07  of  one  per  cent.  Owing  to  the  variation 
of  the  percentage  of  nicotine  in  different  kinds  of  tobacco  and  the  added 
reason  that  tobacco  dips  are  somewhat  tedious  and  disagreeable  to 
make,  it  is  better  to  use  a  reliable  tobacco  extract,  which  may  be  ob- 
tained upon  the  market,  and  exactly  follow  the  instructions  given  for 
the  making  of  the  dip. 

Tobacco  dip  is  not  injurious  to  the  wool,  therefore  it  has  an  advantage 
foi-  use  upon  sheep  which  nuiy  require  treatment  at  a  time  when  they 


128  PARASITES  OF  THE  DOMESTIC  ANIMALS 

cannot  be  safely  or  profitably  sheared.  Its  disadvantages  are  that  it 
sometimes  causes  a  setback  in  the  sheep  by  sickening  them,  and  that  it 
also  occasionally  sickens  persons  who  work  with  it,  especially  if  they  are 
not  tobacco  users. 

Dips  containing  carbolic  acid  are  easily  made  and  rapid  in  their  action, 
but  soon  evaporate  from  the  body,  leaving  the  sheep  unprotected  from 
reinfection.  Furthermore,  in  the  strength  at  which  it  must  be  used  as  a 
reliable  acaricide,  it  causes  the  sheep  to  receive  a  greater  setback  than 
they  do  with  either  the  tobacco  or  lime  and  sulphur  preparation. 

After  Treatment. — The  dipping  is  to  be  repeated  upon  the  entire 
flock  in  twelve  to  fourteen  days.  Where  it  is  necessary  to  place  the 
sheep  in  the  same  pasture  which  they  occupied  before  being  dipped, 
sulphur  should  always  be  an  ingredient  of  the  dip.  This  remains  upon 
the  skin  and  wool  and  protects  from  reinfection  during  the  period  that 
the  acari  may  remain  infective.  In  any  case  it  is  better  to  place  the 
flock  after  the  second  dipping  in  a  pasture  which  they  have  not  been 
upon  for  at  least  five  weeks  previous  to  their  treatment. 

Treatment  of  Psoroptic  Scabies  of  Cattle. — As  psoroptic  scabies  of 
the  ox  may  become  generalized  or  remain  localized  upon  parts  of  the 
body  easily  reached  by  the  tongue,  mercurial  preparations  or  those 
containing  other  poisons  which  may  be  licked  off  should  not  be  em- 
ployed. Where  one  or  two  animals  are  affected  upon  limited  areas  of 
the  body,  ointments  of  sulphur,  such  as  flowers  of  sulphur  one  part, 
lard  four  parts,  may  be  used  with  good  results.  The  remedy  should 
be  preceded  by  the  usual  preparation  of  the  skin.  After  three  days  it 
can  be  washed  ofT  with  soap  and  tepid  water  and  the  application  re- 
peated. 

As  a  convenient,  safe,  and  effective  remedy  probably  the  lime  and 
sulphur  dip  will  give  better  satisfaction  than  any  other  for  the  treat- 
ment of  this  form  of  scab  in  the  ox.  It  should  be  prepared  with  the 
proportion  between  lime  and  sulphur  somewhat  reduced,  as  by  the 
following  formula: 

Flowers  of  sulphur 24  lbs. 

Unslaked  lime 12  lbs. 

Water 100  gals. 

Mix  according  to  directions  given  under  lime  and  sulphur  formulae 
for  scab  in  sheep  (page  125). 

Where  a  small  number  of  animals  are  to  be  treated  the  dip  may  be 
applied  as  a  spray  or  with  a  brush,  working  it  at  the  same  time  well 
into  the  scabs.  In  larger  herds  this  method  is  not  practical,  and  the 
animals  must  be  treated  by  dipping.  Even  though  few  in  the  herd 
give  evidence  of  the  disease,  it  is  safer  to  dip  all,  as  it  is  probable  that  a 
number  of  the  apparently  healthy  have  become  infected. 


TREATMENT  OF  MANGE  AND  SCABIES  129 

Plants  for  dipping  cattle  range  from  the  simple  to  the  elaborate  after 
various  plans.  Directions  and  estimates  for  the  construction  of  such 
plants,  together  with  much  other  valuable  detail  as  to  dipping,  ma}'  be 
obtained  from  the  Bureau  of  Animal  Industry,  United  States  Depart- 
ment of  Agriculture,  upon  application  for  bulletins  relating  to  the  sub- 
ject (Bull.  No.  152). 

The  temperature  of  the  dip  when  used  should  be  from  102°  to  108°  F. 
Each  animal  should  be  kept  m  it  two  minutes  and  be  completely  sub- 
merged before  coming  out.  The  treatment  is  to  be  repeated  in  twelve 
to  fourteen  days. 

After  dipping  the  precautions  against  reinfection,  already  referred  to 
in  connection  with  sheep  scab,  are  to  be  observed. 

Treatment  of  Psoroptic  Scabies  of  the  Horse. — The  treatment  of 
this  scabies  of  the  horse  does  iiot  differ  materiall}^  from  that  given  for 
mange  in  the  same  animal.  From  the  fact  that  the  mites  do  not  burrow 
and  thus  obtain  a  degree  of  protection  from  the  acaricide,  it  is  easier  to 
control  than  the  latter  form. 

The  preliminary  application  of  soap  and  water,  as  directed  in  the 
treatment  of  mange,  should  be  followed  here,  after  which  the  same 
general  acaricide  treatment  may  be  employed.  The  lime  and  sulphur 
preparation  is  probably  of  more  use  for  this  form  of  scab  in  the  horse 
than  for  the  sarcoptic.  It  is  prepared  according  to  the  formulae  given 
for  scab  in  sheep  (page  125),  either  formula  No.  1  or  formula  No.  2  being 
used,  according  to  the  age  and  extent  of  the  lesions.  It  can  be  applied 
as  a  spray  or  with  a  brush,  being  at  the  same  time  well  worked  into 
the  scabs.  The  treatment  should  be  repeated  at  intervals  of  eight  to 
ten  days  until  all  indications  of  the  presence  of  the  mites  have  disap- 
peared. 

The  precautions  against  reinfection,  mvolving  disinfection  of  harness, 
clothing,  stalls,  etc.,  as  given  under  equine  mange,  are  to  be  observed. 

Treatment  of  Chorioptic  Scabies 

Treatment  of  Chorioptic  Scabies  of  the  Horse. — Clip  the  hair  from 
over  the  affected  parts,  usually  from  the  hocks  down.  It  is  well  in  any 
case  to  treat  the  fore  legs  m  the  same  manner  as  these  may  have  been 
infected.  A  portion  of  the  scales  and  crusts  may  be  removed  with  a 
brush,  after  which  the  parts  are  to  be  rubbed  with  a  lather  of  soft  or 
green  soap.  Let  this  remain  for  an  hour,  then  rinse  with  tepid  water, 
scrape,  and  allow  to  dry. 

The  acaricides  mentioned  for  the  treatment  of  other  forms  of  scabies 
ui  the  horse  will  apply  here  as  well.  The  fact  that  the  affected  area  in 
chorioptic  scabies  is  usually  limited  to  the  lower  parts  of  the  legs  per- 
mits of  the  use  of  remedies  which  would  not  be  safe  for  application  over 


130  PARASITES  OF  THE  DOMESTIC  ANIMALS 

lai'ger  surfaces  of  the  body.  Strong  tobacco  decoctions,  benzene,  or  oil 
of  turpentine  may  be  used,  the  latter  shaken  up  in  an  equal  quantity 
of  linseed  oil.  Equal  parts  of  kerosene  and  linseed  oil  also  give  good 
results.  Two  or  three  applications  of  the  remedy  applied  several  days 
apart  usually  suffices  to  bring  about  a  complete  cure. 

The  usual  precautions  against  reinfection  should  be  observed.  The 
bedding  is  to  be  burned  and  utensils  disinfected.  Animals  should  have 
their  legs  regularly  and  carefully  groomed,  and  attendants  should 
be  on  the  lookout  for  sjanptoms  of  a  return  of  the  affection. 

Treatment  of  Chorioptic  Scabies  of  Cattle. — The  curative  procedure 
for  this  scabies  does  not  materially  differ  from  that  for  bovine  mange. 
As  chorioptic  scabies  appears  upon  parts  which  may  be  reached  by 
the  tongue,  preparations  containing  active  poisons  should  be  avoidecl. 
Probably  an  ointment  of  sulphur,  as  sulphur  one  part,  lard  four  parts, 
or  sulphur  two  parts,  potassium  carbonate  one  part,  lard  eight  parts, 
is  most  suitable  for  such  cases. 

Treatment  of  Follicular  Mange 

Treatment  of  Follicular  Mange  of  the  Dog. — Owing  to  the  intra- 
cutaneous location  of  the  parasites,  successful  treatment  of  this  mange 
is  made  very  difficult.  The  prospects  for  eventual  success  will  depend 
much  upon  patience  and  perseverance.  It  is  important  that  the  general 
condition  of  the  animal  be  built  up  as  much  as  possible  by  nutritious 
food  and  thoroughly  sanitary  surroundings.  Such  treatment  as  may 
be  adopted  must  be  prolonged  and  often  repeated  if  carried  out  to 
effectiveness.  The  remedies  given  below  for  the  destruction  of  the 
mites  are  among  those  which  have  been  tried.  The  best  that  can  be 
said  for  them  is  that  they  have  sometimes  given  good  results. 

(1)  Peruvian  balsam  2  parts,  creolin  1  part,  alcohol  20  parts.  An 
objection  to  this  remedy  is  its  expense  in  view  of  the  prolonged  treat- 
ment required.  (2)  Creosote  1  part,  olive  oil  15  to  20  parts;  (3)  benzine 
1  part,  olive  oil  4  parts;  (4)  creolin  1  part,  green  soap  and  alcohol  of 
each  3  parts;  (5)  repeated  applications  over  limited  areas  of  tincture  of 
iodine.  (6)  In  the  clinic  for  small  animals  at  the  School  of  Veterinary 
Medicine,  University  of  Pennsylvania,  some  encouraging  results  have 
been  obtained  from  the  use  of  ichthyol,  prepared  with  lard  or  lanolin 
in  the  proportion  of  one  to  seven. 

Fleming  advises  that  the  topical  treatment  be  accompanied  by  the 
internal  administration  of  sulphur  in  frequent  and  large  doses;  the  sul- 
phur being  excreted  to  some  extent  by  the  skin. 

Treatment  of  Follicular  Mange  of  Swine. — Treatment  of  this  form 
of  mange  in  the  pig  is  rarely  called  for.  If  there  are  perceptible  indica- 
tions of  its  presence  a  treatment  as  recommended  for  dogs  may  be  tried, 


TREATMENT  OF  MANGE  AND  SCABIES  131 

though,  due  to  the  intractability  and  habits  of  pigs,  there  is  probablj- 
even  less  prospect  of  a  complete  destruction  of  the  mites.  The  presence 
of  Demodex,  however,  is  rarely  recognized  in  pigs,  and  the  effects  it 
may  produce  are  far  less  serious  than  in  dogs. 

Treatment  of  Otacariasis  of  the  Dog,  Cat,  and  Rabbit 

Clean  the  ears  of  dogs  and  cats  thoroughly  and  deeply  with  olive  oil. 
It  may  be  applied  with  a  bit  of  cotton  rolled  upon  a  probe  which  should 
be  rotated  as  it  enters  the  deeper  parts.  Nocard's  treatment,  as  stated 
by  Neumann,  is  as  follows:  Naphthol  1  part,  ether  3  parts,  olive  oil 
10  parts.  Inject  into  the  external  auditory  canal  each  day.  After  in- 
jecting close  the  canal  for  ten  to  fifteen  minutes  with  a  pledget  of  cotton. 
This  is  to  prevent  the  evaporation  of  the  ether.  The  ether  causes  the 
remedy  to  penetrate  the  wax>'  Iming  of  the  canal  which  contains  the 
parasites. 

In  the  treatment  of  ra))bits  the  scabs  are  first  to  be  softened  by  a 
thick  lather  of  soft  or  green  soap  which  should  be  allowed  to  remain  for 
an  hour,  rinsed,  and  repeated  as  ma}'  be  necessary  for  deep  crust  forma- 
tion. The  deeper  parts  of  the  ear  ma}'  then  be  cleaned  with  olive  oil 
and  cotton  as  directed  for  dogs  and  cats. 

As  an  acaricide,  the  same  treatment  may  be  employed  as  recommended 
for  otacariasis  in  dogs  and  cats,  applying  the  remedy  with  a  pledget 
of  cotton  over  the  whole  inner  surface  of  the  concha  as  well  as  injecting 
it  into  the  auditory  canal.  An  ointment  of  sulphur,  or  a  liniment  com- 
posed of  benzene  and  olive  oil  equal  parts  may  also  be  used,  either  to 
be  applied  with  a  pledget  of  cotton  rolled  upon  the  end  of  a  probe  or 
stick. 

It  is  a  good  precautionary  measure  to  treat  the  ears  of  all  rabbits 
which  have  been  exposed,  as  there  ma}^  be  infections  of  a  latent  char- 
acter which  will  later  bring  about  another  outbreak  of  the  disease. 


CHAPTER  XII 

MANGE   OF   POULTRY 

The  acari-prodiicing  mange  of  fowls  belong  with  the  genus  Cnemi- 
docoptes,  the  characteristics  of  which  are  described  on  page  103.  There 
are  two  species, — Cn.  mutans  (formerly  Sarcoptes  mutans),  which  pro- 
duces the  condition  known  as  scaly  leg,  and  Cn.  gallince  {Cn.  Icevis) 
which  attacks  the  skin  at  the  attachment  of  the  feathers. 

Mange  of  the  Legs  ("  Scaly  Leg  "). — The  burrowing  mite  of  leg 
mange  most  often  attacks  the  feet  and  legs  of  chickens  of  the  heavier 
breeds,  as  the  Brahma,  Dorking,  and  Cochin  China,  less  frequently 
turkeys,  pheasants,  and  pigeons. 

The  mites  live  under  the  epidermic  scales  from  the  tarsal  joint  down- 
ward, including  the  upper  part  of  the  toes.  In  this  location  iYiey  deposit 
their  eggs  and  multiply,  the  irritation  of  their  presence  soon  being 
manifested  by  the  formation  of  a  white  powdery  matter  which  elevates 
the  scales.  Due  to  the  exuded  serum,  this  matter  assumes  a  lardaceous 
nature,  adhering  to  and  soon  covering  the  foot.  Gradually  rough  crusts 
are  formed  in  the  lower  layers  of  which  numerous  mites  may  be  found. 
The  scabs  adhere  closely  to  the  skin,  and,  when  removed,  reveal  an 
irritated  and  bleeding  surface  (Fig.  75). 

The  course  of  the  disease  is  slow,  running  several  months  to  a  3'ear. 
There  is  a  moderate  pi-uritus  which  the  fowl  indicates  by  restlessness 
and  picking  at  the  scabs  with  the  beak.  As  the  crusts  increase  there 
is  a  mechanical  interference  with  flexion  of  the  joints  which  makes 
either  moving  about  or  standing  difficult.  As  a  consequence  the  animal 
often  squats  down  with  the  legs  extended  and  remains  in  this  position 
with  infrequent  efforts  to  rise.  In  such  severe  cases  arthritis  is  likely  to 
appear,  and  one  or  even  all  of  the  toes  may  drop  off.  When  the  disease 
has  advanced  over  several  months  we  have  the  usual  systemic  accom- 
paniment of  prolonged  mange;  there  is  loss  of  appetite,  cachexia,  and 
stupor  which  is  usually  followed  by  death. 

Treatment. — Treatment  must  begin  with  softening  of  the  scabs  with 
soft  soap,  appHed  by  hand  or  by  soaking  in  warm  soapj^  water.  They 
may  then  be  removed  by  manipulation  with  the  hands  or  with  a  brush, 
care  bemg  taken  in  this  operation  to  cause  as  little'injury  to  the  skin  as 
possible.  When  the  parts  are  dr,y,  apply  Peruvian  balsam,  either  alone 
or  made  up  in  the  proportions  of  balsam  2  parts,  creolin  1  part,  alcohol 
20  parts.    The  ointment  of  Helmerich,  as  recommended  for  scabies  in 


IMANGE  OF  POULTRY 


133 


other  animals,  is  one  of  the  best  remedies  for  this  scab.  Others  perhaps 
as  effectual  are  (1)  creosote  1  part,  lard  20  parts;  (2)  benzene  1  part, 
olive  oil  10  parts;  (3)  carbolized  vaseline  (5%),  or  (4)  an  ointment  of 
carbolic  acid  1  part,  lard  20  parts.  The  stronger  acaricides  should  not 
be  used  upon  young  chicks.  For  these  the  ointment  of  Helmerich  or 
Balsam  of  Peru  are  quite  suitable.  The  application  may  be  washed  off 
and  repeated  as  necessary'. 

To  prevent  contagion  and  reinfection,  diseased  fowls  should  be  re- 
moved from  the  healthy  and  the  quarters  subjected  to  cleaning  up  and 
disinfection,  especial  attention  bemg  given  to  roosts  and  other  places 
where  the  fowls  are  in  the  habit  of  perching. 


Fig.  74. — Cnemidocoptes    mutans,    male    and    female    (after 
Osborn,  Bull.  No.  5,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agr.). 


Mange  of  the  Body,  or  Depluming  Mange. — The  depluming  mite, 
Cnemidocoptes  gallince,  is  closely  related  to  the  mite  of  foot  mange  and 
it  may  easily  be  mistaken  for  the  same  species  where  the  two  forms  of 
mange  coexist.  The  Ijody  form  usually  has  its  begmning  on  the  back, 
near  the  msertion  of  the  tail-feathers.  More  rarely  the  head  and  upper 
part  of  the  neck  are  first  attacked.  From  these  regions  it  spreads  to 
adjacent  parts  of  the  body. 

The  disease  is  accompanied  by  the  production  of  an  abundance  of 
epidermic  scales,  irritation,  and  itching  which  impels  the  fowl  to  pluck 
at  the  feathers.  These  easily  drop  out  or  are  broken  off,  leaving  a  bald 
or  partly  denuded  skin  which  is  but  little  thickened  and  remams  normally 
smooth  and  elastic. 

The  acaricide  treatment  employed  may  be  the  same  as  for  foot  mange. 
AVhere  a  numljcr  of  birds  are  affected  they  may  be  treated  by  dipping 
for  several  successive  days  m  a  sulphur  bath.  The  same  precautions 
against  contagion  and  remfection  are  to  be  observed  as  for  the  leg  form. 
In  this  connection  it  is  well  to  repeatedly  disinfect  the  feet  of  roosters. 


134 


PARASITES  OF  THE  DOMESTIC  ANIIMALS 


Cytoleichus  nudus. 


as  the  disease  is  readily  conveA^ed  from  the  l^ack  of  one  hen  to  another 
in  treading. 

Family  V.  Cytoleichid^ 

Acarina  (p.  94). — This  family  contains  two  genera,  Cytoleichus  and 
Laminosioptes,  each  with  one  species  causmg  a  deep-seated  acariasis  m 
birds. 

C3^toleichidse  (p.  134). — The  body  is  rounded, 
almost  bald,  and  whitish  in  color.  The 
mouth  parts  are  conical.  The  legs  have  five 
articles  and  are  strong  and  elongated;  all 
terminate  by  a  simple  stalked  sucker.  The 
ovigerous  female  is  500  to  600  microns  long 
by  350  to  400  microns  broad.  She  may  pro- 
duce either  larvae  or  eggs. 

Colonies  of  these  parasites  live  in  the  air 
passages  and  air  sacs  of  fowl. 

Laminosioptes  cysticola.  Cytoleichidae 
(p.  134). — The  body  is  twice  as  long  as 
broad;  color  grayish.  On  the  dorsal  surface 
are  several  pairs  of  bristles,  a  long  pair  ex- 
tending from  the  posterior  extremity.  The 
mouth  parts  and  the  two  first  pairs  of  legs 
are  carried  upon  the  anterior  third  of  the 
body  which  is  separated  from  the  posterior 
portion  by  a  transverse  furrow.  The  legs 
are  short,  smooth,  and  provided  with 
suckers,  which  are  not  permanent  upon  the 
anterior  pair.  The  ovigerous  female  is  250 
to  260  microns  long  b^'  100  to  110  microns 
broad. 

Parasitic  in  subcutaneous  connective  tis- 
sue of  fowl. 

The  C3'toleichus  species  enter  the  respir- 
atory passages  and  pass  to  the  deeper  air 
channels,  even  to  the  air  canals  in  the  bones. 
From  their  relatively  large  size  and  whitish 
color  they  may  be  readily  seen  with  the  naked  eye,  usually  in  colonies 
of  more  or  less  number.  Ordinarily  these  parasites  do  not  cause  suf- 
ficient disturbance  to  betraj'  their  presence  during  the  life  of  their  host. 
If  in  exceptionally  large  numbers  they  maj'  cause  attacks  of  coughing 
by  irritation  of  the  bronchial  mucosa. 

Laminosioptes  cyUicola  lives  m  the  subcutaneous  connective  tissue, 
especially  in  regions  where  this  is  loose,  as  the  neck,  breast,  sides,  and 


Fig.  75. — Foot  of  fowl  affected 
with  scaly  leg. 


IMANGE  OF  POULTRY  135 

thigh.  Where  nian}^  are  present  they  cause  irritation  with  the  forma- 
tion of  yellowish,  oval  nodules.  These  are  about  0.5  mm.  by  1  mm. 
in  dimensions,  and  a  large  number  of  them  may  cover  a  small  area.  They 
are  soft,  granular  or  calcareous,  and  may  contam  the  dead  parasites. 
The  health  of  the  host  does  not  appear  to  l)e  affected  by  the  lesions 
which  these  parasites  produce. 


CHAPTER  XIII 

THE  TICKS 

There  has  been  considerable  difference  of  opinion  among  various 
authors  as  to  the  S3'stematic  arrangement  of  the  ticks.  They  have 
been  brought  into  one  family, — Ixodidae,  in  which  two  subfamilies  are 
distinguished. — Argasinse  and  Ixodmse,  and,  again,  these  two  subgroups 
have  been  considered  as  distinct  families.  The  arrangement  adopted 
here,  which  raises  the  ticks  to  the  rank  of  a  superfamily,  is  that  of  Banks 
(1894)  and  as  followed  by  Salmon  and  Stiles  (1901). 

Structure  of  Ticks  in  General. — The  proper  study  and  differentiation 
of  the  ticks  requires  some  knowledge  of  the  external  parts  and  an  under- 
standing of  the  teclmical  terms  which  are  used  m  reference  to  them. 
Conformmg  to  the  general  characteristics  of  the  order  Acarma  to  which 
they  belong,  the  ticks  have  a  body  in  which  the  cephalothorax  and 
abdomen  are  not  demarcated  and  this  bears  certain  structures  possessing 
variations  as  to  location  and  form  which  serve  as  defining  characters 
for  the  various  subgroups  and  species.  The  parts  more  commonly 
referred  to  with  their  technical  names  follow : 

1.  The  Capitulum  (Fig.  76)  is  the  "head,"  ''false  head,"  or  rostrum,  as 
it  is  variously  termed.  It  projects  from  the  anterior  extremity  in  the 
Ixodidae.  In  the  Argasidae,  except  in  the  larval  stage,  it  is  upon  the 
under  surface  of  the  anterior  extremity.  The  structure  consists  of  a 
number  of  parts,  as  follows : 

(a)  The  Basis  Capitidi  (Fig.  76,  b)  is  the  hard  base  of  the  capitulum; 
the  basal  ring  or  mouth  shield. 

(b)  The  Hijpostome  (Fig.  76,  h)  or  "labium"  or  "radula"  of  various 
authors  is  a  median  ventral  structure  rising  from  the  basis  capituli  and 
bearing  recurved  teeth. 

(c)  The  Chelicerce  (Fig.  76,  c),  "mandibles,"  or  "jaws"  are  paired 
elongate  structures,  one  on  each  side  of  the  median  line,  lying  dorsal 
to  the  hypostome.    Dorsal  to  these  is  the  hood  or  sheath  of  the  chelicerse. 

The  hypostome,  chelicerse,  and  hood  constitute  the  haustellum,  or,  as 
it  is  commonly  called,  the  "beak,"  and  it  is  these  structures  which  pen- 
etrate the  skin  of  the  animal  upon  which  the  tick  attaches. 

(d)  The  Palpi  (Fig.  76,  p)  are  articulated  structures,  one  on  each 
side  of  the  haustellum,  and  inserted  antero-laterally  upon  the  basis 
capituh. 

2.  The  Scutum  (Fig.  77),  or  dorsal  shield — present  in  the  Ixodidae, 


THE  TICKS 


137 


Fig.  76. — Capitulum  (rostrum), 
of  an  argasid  tick:  h,  hypostome; 
c,  chelicerae;  p,  palpi;  b,  basis 
capituli. 


absent  in  the  Argasidae — is  a  hard,  plate-Hke  structure  located  inmie- 
diately  posterior  to  the  capituhim.  In  the  male  it  usually  covers  the 
entire,  or  almost  the  entire,  dorsal  surface, 
in  n\nnphs  it  covers  the  anterior  portion; 
while  in  the  adult  female  it  is  much  smaller 
and  confined  to  the  anterior  portion  of  the 
liody. 

3.  Dorsum. — This  term  refers  to  the 
whole  dorsal  surface  of  the  body. 

4.  Festoons  (Fig.  82)  are  uniform  rect- 
angular areas  into  which  the  posterior  mar- 
gin of  the  body  is  divided  up.  Usually 
eleven  may  be  more  or  less  distinctly  rec- 
ognized. They  are  most  distinct  in  unfed 
specimens,  but  almost  or  entirely  disap- 
pear in  distended  females.  They  are  not 
present  m  all  forms. 

5.  Punctations  are  circular  depressions 
upon  the  integument  from  which  fre- 
quently issue  hairs. 

6.  Ornamentation  refers  to  enamel-like  coloration  which  may  be  pres- 
ent on  the  scutum,  capitulum,  or  other  parts.  Ticks  upon  which  this 
coloration  occurs  are  re- 
ferred to  as  ornate. 

7.  Venter. — This  term 
refers  to  the  whole  ventral 
surface  of  the  body. 

8.  The  Spiracles  (Figs. 
78  and  78,  a) — also  called 
stigmata,  stigmal  plates, 
and  peritremes — are  two 
respiratory  organs  sit- 
uated ventro-laterally.  In 
the  Ixodidse  they  are  sit- 
uated posterior  to  the 
attachment  of  the  fourth 
pair  of  legs;  in  the  Arg- 
asidae they  are  ))etween 
the  third  and  fourth  pairs. 
The  entire  structure  may 
be  considered  as  the 
stigmal  plate  or  peritreme 
with  an  opening  known  as 
the  spiracle  or  stigmal  aperture.     The  stigmal  plates  vary  in  form  and 


Fii;.  77. — Capitulum  (head),  .•scutum  (.shield),  and 
foreleg  of  Margaropus  annulatu.s  (from  photomicro- 
graph of  mounted  specimen,  by  Hoedt). 


138 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


structure  in  different  species;  they  may  be  circular,  oval,  or  comma- 
shaped. 

9.  The  Genital  Pore  is  a  transverse  ventro-median  slit,  situated  ante- 
riorly between  the  at- 
tachments of  the  first 
three  pairs  of  legs. 

10.  The  Anus  is  in  the 
ventro-median  line,  pos- 
terior to  the  attachment 
of  the  last  pair  of  legs. 

11.  The  Anal  Shields 
are  four  elongate  struc- 
tures lateral  to  the  anus. 

They  are  present  only  in  males  of  certain  genera. 

12.  Legs. — There  are  four  pairs  of  legs  in  the  adult  males  and  females 
and  in  the  nymphs  (octopod).    In  the  larvae  there  are  three  pairs  (hex- 


FiG.   78. — Stigmal  plates  of  ticks:  1,  Margaropus 
Ixodes;  3.  Dermacentor. 


Fig.  78A. — Stigmal  plate  of  Margaropus  annulatus  (photomicro- 
graph of  mounted  specimen,  by  Hoedt). 

apod).  The  pairs  are  numbered  I  to  IV  from  before  to  behind.  They 
are  composed  of  six  articles  or  segments  which  are  united  by  articul- 
ations. 

13.  The  Coxa  or  first  article  is  an  immovable  portion  which  lies  flat 
upon  the  body  and  upon  which  the  first  movable  article  is  articulated. 


THE  TICKS 


139 


14.  Bifid  Coxce  bear  two  spurs  and  are  deeply  incised.  When  tren- 
chant they  have  a  knife-hke  margin. 

Several  stages  are  passed  through  in  the  development  of  the  ticks. 
From  the  eggs  are  hatched  the  six-legged  (hexapod)  larvce,  often  referred 
to  as  the  "seed  ticks"  (Plate  II,  Fig.  6).  These  are  very  small  but 
may  be  seen  without  the  aid  of  magnification.  The  legs  are  relatively 
much  longer  than  in  the  adults. 

The  nymph  stage  is  reached  after  molting,  when  a  fourth  pair  of  legs 
appears  posterior  to  the  third  pair  (octopod). 

The  change  from  the  nymphal  to  the  adult  stage  is  marked  by  another 
molting,  and  sexual  maturity  is  reached. 

After  fertilization  b}^  the  male,  the  female  slowly  enlarges  and  be- 
comes the  ovigerous  or  egg-containing  female.  Upon  repletion  she  drops 
to  the  ground  and  proceeds  to  deposit  her  eggs. 

Superfamily  Characteristics.  Acarina  (p.  94). — The  Ixodoidea  are 
all  blood-sucking  parasites  on  animals.  They  have  a  movable  capitulum 
consisting  of  a  basal  portion  (basis  capituli),  protrusi})le  serrate  chel- 
icerse,  a  rigid  serrate  hypostome,  and  a  pair  of  palps.  The  breathing 
apertures  are  situated  posteriorly. 

The  superfamily  Ixodoidea  is  divided  into  two  families, — Argasidae 
and  Ixodidse. 

Family  I.  Argasid^ 

Ixodoidea  (p.  139). — The  ticks  belonging  with  this  family  have  little 
sexual  dimorphism  as  compared  with  the  Ixodid*.  The  capitulum, 
instead  of  being  terminal,  occupies  in  adults  the  ventral  face  of  the 


■^^^ 


Fig.  79. — Argas  miniatus:  Fig.  3,  dorsal  view;  3a,  ventral  view;  3c,  larva   (after  Os- 
born,  from  Marx,  Bui.  No.  5,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agr.). 

cephalothorax.  The  palps  are  leg-like,  the  articles  very  movable  on 
each  other.  The  scutum  is  absent.  The  coxa^  are  unarmed;  tarsi  with- 
out ventral  spurs. 

The  family  has  two  genera, — Argas  and  Otobius. 

1.  Argas  miniatus  (A.  americanus)  (Fig.  79).  The  Fowl  Tick.  Ar- 
gasidae (p.  139). — The  lK)dy  is  ovoid,  flattened,  with  edges  very  thin. 


140  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Depending  on  the  stage  of  engorgment,  the  color  varies  from  Hght 
reddish  to  dark  brown.  The  capitulum  has  four  long  hairs,  all  directed 
forward.  The  adult  females  are  about  8.5  mm.  (5/16  of  an  inch)  in 
length.  The  males  are  slightly  smaller,  but  are  not  easily  distinguish- 
able. 

Occurrence  and  Habits. — Commonly  called  the  "fowl  tick"  or 
"  adobe  tick,"  this  species  is  widely  distributed.  It  is  a  parasite  of  fowl  in 
Europe,  Asia,  Africa,  and  Australia,  in  Mexico  and  the  Southern  United 
States.  In  its  habits  it  is  comparable  to  the  bedbug,  commg  out  to 
feed  upon  its  host  at  night  and  retreating  after  engorgment  to  cracks, 
crevices,  or  other  darkened  hiding  places  to  remain  during  the  day.  In 
these  retreats  the  females  deposit  large,  reddish  brown  eggs,  usually 
several  layings,  in  masses  containing  up  to  a  hundred  or  more  eggs  in 
each.  Herms  (1915)  gives  the  further  life  history  as  follows:  "Hatching 
takes  place  in  from  three  to  four  weeks.  The  larvee  are  six-legged  and 
very  active,  attacking  a  host  apparently  as  readily  by  day  as  by  night. 
Once  attached  the  larvae  feed  for  about  five  days,  occasionally  longer, 
remaining  firmly  attached  during  this  time.  At  the  end  of  this  feeding 
period  the  larvae  detach  themselves  and  then  crawl  away  from  their 
host,  hiding  in  some  convenient  crevice  near  by.  The  larvae  molt  in 
about  a  week,  when  the  fourth  pair  of  legs  appears  and  they  are  now  in 
the  first  nymphal  stage,  appearing  like  miniature  adults.  Nocturnal 
feeding  now  takes  place  and  in  ten  or  twelve  days  another  molt 
occurs  and  the  second  nymphal  stage  is  reached.  Again  the  tick  at- 
taches itself,  being  now  able  to  engorge  itself  in  about  an  hour;  again 
after  the  expiration  of  something  over  a  week  a  third  molt  takes  place 
and  the  adult  stage  is  reached.  The  adults  are  able  to  engorge  them- 
selves in  from  twenty  to  forty-five  minutes." 

Effect. — When  attacking  in  large  numbers  these  parasites  extract 
large  quantities  of  blood  and,  furthermore,  cause  much  irritation  and 
unrest  among  the  flock.  As  a  result  the  animals  become  unthrifty, 
weak,  and  nonproductive. 

Argas  miniatus  has  been  proven  to  be  the  carrier  of  the  spirochete 
(Spirocheta  gaUinarum)  causing  fowl  spirochetosis  or  Brazilian  sep- 
ticemia of  fowls  (p.  327). 

Control. — For  the  eradication  of  this  pest  the  same  general  methods 
may  be  taken  as  recommended  for  bedbugs  of  the  hen  house  (p.  92). 
The  ends  of  roosts  should  be  repeatedly  covered  with  tar  or  wrapped  in 
waste  soaked  Avith  crude  oil.  Nesting  and  trash  should  be  burned  and 
the  interior  sprayed  with  kerosene.  All  woodwork  about  the  buildings 
should  be  free  from  bark,  as  this  affords  a  favorable  hiding  place  for  the 
ticks.  It  is  well  to  repeat  the  treatment  with  kerosene  at  least  once  a 
month  during  the  season  that  the  ticks  are  active, 

2.  Otobius  megnini  (Ornithodorus  megnini,  Fig.  80).     The  Spinose 


THE  TICKS 


141 


Ear  Tick,  Argasidse  (p.  139). — The  boch'  is  oval,  broader  anteriorly  than 
posteriorly.  The  female  is  5-6  mm.  (V4  of  an  inch)  in  length  and  about 
3  nmi.  (Vs  of  an  inch)  in  breadth.  The  nymphs  are  covered  with  nu- 
merous spines,  a  fact  which  has  given  to  this  species  the  common  name 
''spinose  ear  tick." 

Occurrence  and  Habits. — This  tick  occurs  in  the  ears  of  horses  of 
]\Iexico  and  the  Southwestern  States.  Its  attack  is  not  confined  to 
horses  and  mules;  it  also  attacks  the  ears  of  cattle  and  occasionally  other 
domestic  animals  and  man.  The  larval  ticks  reach  the  head  of  the  graz- 
ing host  animal  from  weeds  or  other  vegetation  upon  which  they  have 
crawled  immediately  after 
hatching.  Having  gained  en- 
trance to  the  ear,  they  attach 
deeph'  in  the  folds  where  the}- 
feed  for  about  five  days. 
They  then  molt  and,  as 
n\Tnphs  with  spinose  bodies, 
contmue  to  infest  the  ear  and 
feed  for  several  weeks.  The 
minphs  then  leave  the  host, 
again  molt,  and  becoming 
unspmed  adults,  the  females 
are  fertilized  and  soon  begin 
depositing  their  eggs. 

Effect. — In  their  attach- 
ment to  the  lining  of  the 
conchse  the  spinose  ticks 
cause  much  irritation  which 
the  animal  indicates  by  shak- 
ing its  head,  or  it  may  be 
wrought  up  to  a  high  degree  of  nervous  excitement.  The  ticks  are  said 
to  be  responsible  for  much  deafness  among  domestic  annuals,  and, 
especially  among  young  animals,  they  are  considered  as  a  cause  of  se- 
rious illness  and  even  death. 

Treatment. — Good  results  have  been  obtained  by  flooding  the  ear 
with  carbolized  oil.  This  closes  the  breathing  apertures  of  the  ticks  and 
causes  them  to  release  their  attachment,  after  which  they  may  be  re- 
moved with  a  cotton  swab  or  forceps  and  destroyed. 


Fig.  80. — Otobius  megnini:  dorsal  and  ventral 
view  of  nymphal  form,  with  details  (after  Osborn, 
from  IVIarx,  Bull.  Xo.  5,  Bureau  of  Entomology, 
U.  S.  Dept.  of  Agr.). 


Family  II.  Ixodid.e 

Ixodoidea  (p.  139). — The  most  prominent  differential  character  by 
which  these  ticks  may  be  distinguished  from  those  of  the  family  Ar- 
gasidse is  the  presence  of  a  scutum,  located  inunediately  posterior  to 


14-2  PARASITES  OF  THE  DOMESTIC  ANIMALS 

the  capitiiluin,  which  is  terminal  and  not  upon  the  ventral  face  of  the 
cephalothorax  as  in  the  Argasidse.  Sexual  dimorphism  is  marked,  the 
dorsal  surface  of  the  males  being  almost  covered  by  the  scutum.  In 
the  distended  female  the  scutum  appears  as  a  small  shield  directly  be- 
hind the  capitulum.  Only  the  females  are  capable  of  great  distension. 
The  spiracles  are  posterior  to  the  fourth  coxae.  The  eyes,  if  present,  are 
situated  laterally  upon  the  scutum. 

Nine  genera  have  been  described  under  the  famity  Ixodidae,  as  fol- 
lows: Ixodes,  Hsemaphysalis,  Dermacentor,  Rhipicentor,  Rhipicephalus-, 
Margaropus,  Boophilus,  Hyalomma,  and  Amblyomma. 

Four  of  the  above, — Ixodes,  Dermacentor,  Margaropus,  and  Am- 
blyomma,— -contain  species  occurring  upon  cattle  and  other  animals  in 
the  United  States.  The  generic  characteristics  of  these  are  given  by 
Nuttall  and  Warburton  (A  Monograph  of  the  Ixodoidea,  1911)  as 
follows: 

1.  Ixodes. — Inornate,  without  eyes  and  without  festoons;  spiracles 
round  or  oval;  palps  and  basis  capituli  of  variable  form;  coxae  either  un- 
armed, trenchant,  spurred,  or  bifid;  tarsi  without  spurs.  Sexual  di- 
morphism pronounced,  especially  with  regard  to  the  capitulum.  In 
the  male  the  venter  is  covered  by  non-salient  plates:  one  pregential, 
one  median,  one  anal,  two  adanal  and  two  epimeral  plates.  Anal  groove 
surrounding  anus  in  front. 

2.  Dermacentor. — Usually  ornate,  with  eyes  and  festoons;  with 
short,  broad  or  moderate  palps  and  basis  capituli  rectangular  dorsally. 
In  some  species  coxae  I  to  IV  of  the  male  increase  progressively  in  size; 
in  all  species  coxa  IV  is  much  the  largest ;  the  male,  moreover,  shows  no 
ventral  plates  or  shields.  Coxa  I  bifid  in  both  sexes.  Anal  groove  con- 
touring anus  behind.    Spiracles  suboval  or  comma-shaped. 

3.  Margaropus. — Inornate,  with  eyes,  but  without  festoons,  with 
short  palps  and  capitulum  intermediate  between  that  of  Rhipicephalus 
and  Boophilus;  highly  chitmized;  the  unfed  adults  of  large  size.  The 
female  with  very  small  scutum.  Coxae  conical,  unarmed  but  for  a  small 
spine  posteriorly  on  coxa  I.  The  male  with  a  median  plate  prolonged 
in  two  long  spines  projecting  beyond  and  to  either  side  of  the  anus; 
with  coxae  similar  to  those  of  the  female;  legs  increasing  progressively 
in  size  from  pair  I  to  IV,  the  articles,  especially  of  leg-pair  IV,  greatly 
swollen.  When  replete,  the  male  shows  a  caudal  protrusion.  Anal 
groove  obsolete.    Spiracles  rounded  or  short  oval  in  both  sexes. 

4.  Amblyomma. — Generally  ornate,  with  eyes  and  with  festoons. 
With  long  palps;  of  which  article  II  is  especially  long,  basis  capituli  of 
variable  form.  The  male  without  adanal  shields,  but  small  ventral 
plaques  are  occasionally  present  close  to  the  festoons.  Anal  groove 
contouring  anus  behmd.    Spiracles  subtriangular  or  comma-shaped. 

Six  species  are  found  upon  cattle  and  other  domestic  animals  in  this 


THE  TICKS 


143 


countiy,  the  following  brief  descriptions  of  which  are  taken  principally 
from  those  given  by  ^lohler  (Bull.  No.  78,  Bureau  of  Animal  Industr}-, 
1905;  Farmers'  Bull.  No.  569,  1914).  The  parts  described  are  those  of 
the  adult  female. 

1.  Ixodes  ricinus  (Fig.  81).  The  Castor-bean  Tick.  Ixodes  (p. 
142). — The  body  is  ovoid  in  shape,  narrower  anteriorly  than  posteriorly; 
lead  colored,  with  a  diversity  of  3'ellowish  red,  brown,  or  gray.  Festoons 
are  absent.  The  mature  female  is  three-eighths  to  seven-sixteenths  of 
an  inch  m  length.  The  legs  are  thin  and  dark  brown  in  color.  The 
capitulum  and  scutum  are  a  shiny  dark  brown  or'  chestnut  brown; 
scutum  pentagonal  with  prominent  lat- 
eral borders.  The  palpi  are  well  de- 
veloped and  extend  outward  upon  each 
side. 

This  tick  has  been  collected  from  sheei\ 
goats,  cattle,  horses,  deer,  dogs,  foxes, 
cats,  rabbits,  birds,  and  man.  It  i- 
widely  distributed  in  the  United  States. 

2.  Ixodes  hexagonus.  The  European 
Dog  Tick.  Ixodes  (p.  142).— The  body 
is  oval  in  shape  and  of  an  ashy  color; 
festoons  absent.  The  legs  are  longer  and 
more  robust  than  those  of  the  cattle  tick. 
The  capitulum  and  scutum  are  brownish 
red  in  color  and  similar  to  those  of 
Ixodes  ricinus  in  shape.  The  palpi  are 
longer  and  more  prominent  than  in  the 
cattle  tick  and,  like  those  of  Ixodes  ridniis,  extend  outward. 

This  species  has  been  collected  from  dogs,  cattle,  sheep,  foxes,  rabbits, 
squirrels,  gophers,  cats,  birds,  man,  and  other  hosts  in  the  Eastern 
United  States,  but  is  less  common  in  this  country  than  the  other  species 
here  described. 

3.  Dermacentor  reticulatus  (D.  occidentalis).  The  Net  Tick. 
Dermacentor  (p.  142). — The  body  is  oblong  oval,  five-eighths  of  an  inch 
long,  and  of  a  deep  brown  or  slate  color.  The  legs  are  brown  and  of 
moderate  length.  There  are  eleven  festoons  about  the  posterior  margin 
of  the  ])ody  which  in  the  adult  become  shallow  or  effaced.  The  scutum 
has  a  silveiy-white  metallic  rust  extending  along  the  two  sides  and 
posterior  portion. 

Found  on  man,  cattle,  horses,  sheep,  and  deer.  In  this  country  it 
seems  to  be  most  common  in  the  West,  especially  in  California,  Texas 
and  New^  Mexico. 

4.  Dermacentor  variabilis  (D.  electus,  Fig.  82).  The  American 
Dog  Tick  or  Wood  Tick.    Dermacentor  (p.  142). — This  tick  resembles 


Fig.  cSl. — Ixodes  ricinus — enlarged 
(after  Osborn,  Bull.  No.  5,  Bureau 
of  Entomology,  U.  S.  Dept.  of  Agr.). 


144 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


D.  reticulatus  so  closeh^  that  a  hand  lens  is  necessary  to  distinguish  be- 
tween them.  The  body  is  oblong  oval  in  shape  and  may  measure  as 
much  as  three-fifths  of  an  inch  in  length.  It  can  be  distinguished  from 
the  Texas-fever  tick  by  the  capitulum  and  scutum  which  are  longer  and 
broader.  Extendmg  anteriorly  along  each  side  of  the  scutum  there  are 
lines  of  yellowish  white  rust,  separated  by  a  central  brownish  area. 
There  are  eleven  festoons  on  the  posterior  margin  of  the  body,  most 
distmct  in  the  3'oung  female. 

This  tick  has  been  found  on  man,  cattle,  dogs,  horses,  and  other  an- 
imals, especially  in  the  Eastern  United  States. 


Fig.  82. — Dermacentor  variabilis:  male — enlarged  (after  Os- 
born,  Bull.  No.  5,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agr.). 

5.  Margaropus  annulatus   (Boophilus  annulatus,   B,  bovis).     The 

Texas-fever  or  Cattle  Tick.  Margaropus  (p.  142). — This  tick  may  be 
distinguished  from  the  other  five  by  the  small  size  and  the  color  of  the 
capitulum  and  scutum,  the  lateral  borders  of  which  are  straighter  and 
more  parallel.  These  parts  are  short  and  relatively  broad  and  in  color 
reddish  brown  or  chestnut  brown.  The  body  is  oblong  oval  in  shape 
and  may  reach  a  length  of  one-half  an  inch.  The  color  may  be  dull 
yellow  or  olive  brown.  Often  it  is  mottled  with  irregular  areas  of 
yellow  and  brown  or  streaked  with  wavy  lines  of  these  colors.  Festoons 
are  absent.    The  legs  are  brown,  moderately  long,  and  very  slender. 

This  tick  is  found  principally  on  cattle,  less  frequently  on  horses, 
mules,  and  asses. 


THE  TICKS  145 

6.  Amblyomma  atnericanum.  The  Lone  Star  Tick. — Amblyomma 
(p.  142). — The  body  is  oval  and  in  color  yellowish  gray  or  brown. 
When  not  distended,  the  body-surface  is  rough  and  puckered.  Festoons 
are  present.  The  scutum  extends  backward  a  short  distance  to  form  a 
triangle,  at  the  apex  of  which  is  a  white  or  yellowish  spot,  from  which 
the  tick  derives  its  name  "Lone  Star."  The  mature  female  may  reach 
a  length  of  one-half  an  inch.    The  legs  are  long  and  thin. 

This  species  has  been  found  on  cattle,  dogs,  horses,  sheep,  goats,  hogs, 
and  man.    It  is  very  widely  distril)uted  in  the  United  States. 

All  of  these  ticks  show  longitudinal  grooves  ujion  the  dorsal  surface 
of  the  body  which  are  most  distinct  a  few  days  after  the  tick's  repletion 
and  removal  from  the  host.  These  furrows  vary  considerably  in  different 
members  of  the  same  species  and,  though  some  authors  appear  to  attach 
importance  to  them,  they  can  hardly  be  considered  of  much  value  as  an 
aid  in  recognition.  Color  is  also  unreliable  in  the  identification  of 
genera  and  species,  as  this  varies  with  the  stages  in  the  tick's  develop- 
ment and  may  change  variously  in  adult  ticks  of  the  same  species. 

The  Texas-fever  Tick. — Kilborne,  of  the  Bureau  of  Animal  Industry, 
proved  conclusively  by  field  experiments  conducted  in  1889  and  1890 
that  it  is  only  through  the  bite  of  this  tick  that  Texas-fever  can  be 
naturally  transmitted.  Economically,  therefore,  Margaropus  annulatus 
(Plates  I  and  II),  the  Texas-fever  tick,  is  the  most  important  for  con- 
sideration. Other  ticks  not  concerned  in  the  transmission  of  Texas- 
fever  have  been  mentioned  here  as  occiu'ring  upon  cattle,  all  having 
the  same  successive  stages  in  their  development,  namely,  oval,  larval, 
nymphal,  and  adult  male  and  female.  Before  molting  and  transforming 
from  one  stage  to  the  other  these  ticks  fall  from  their  host,  after  the 
transformation  seeking  a  new  host.  That  this  is  not  true  in  the  case 
of  the  Texas-fever  tick  was  shown  by  Dr.  Cooper  Curtice,  of  the  Bureau 
of  Animal  Industry,  in  1891.  He  established  the  fundamental  facts 
in  the  life  history  of  this  tick  and  showed  that  it  remains  upon  its  host 
from  the  time  that  it  attaches  as  a  larva  until  it  drops  to  the  ground 
replete  and  ready  to  deposit  its  eggs  (Tables,  p.  151).  Careful  observa- 
tions by  the  Zoological  Division  of  the  Bureau  have  supplied  valuable 
data  relative  to  the  biology  of  this  tick,  and  much  detailed  information 
has  been  published  by  the  Bureau  pertaining  to  this  and  to  tick  control 
and  eradication.  In  this  connection,  it  may  be  of  service  to  mention 
here  the  following  titles,  any  of  which  can  be  obtained  upon  application 
to  the  Superintendent  of  Documents,  Government  Printing  Office, 
Washington,  D.  C. 

Texas  Fever,  Methods  for  its  Prevention,  by  John  R.  Mohler.  Bull. 
No.  78  (1905). 

Texas  or  Tick  Fever  and  its  Prevention,  l)y  John  R.  Mohler.  Farmers' 
Bull.  No.  258  (1906). 


Plate  I. — Margaropus  annulatus:  1,  Male,  dorsal  view;  2,  Female,  dorsal  view;  3, 
Male,  ventral  view;  4,  Female,  ventral  view;  5,  Claw  and  pulvillus;  6,  Lower  surface  of 
first,  second,  and  third  segment  of  leg;  7,  Stigmal  plate.  (After  Osborn,  from  Curtice, 
Bull.  No.  5,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agr.). 


4        4a 


Plate  II.— MarRaropus  anruilatus:  1,  Front  foot,  showing  single  spur;  la,  Supposed 
sense  organs;  2,  Hind  foot,  showing  double  spur;  3,  Head  of  female;  4,  4a,  4b,  4e,  Fcrnale 
ticks,  natural  size,  shown  at  different  stages  of  feeding;  5,  Egg;  G,  Larval  or  "seed"  tick; 
7,  Dorsal  surface  of  the  mouth  parts  of  female — a,  mandible;  b,  labrum;  c,  palpus;  d, 
mouth  ring;  e,  spots  covered  with  papilla;  S,  Labium  and  mandibles;  8a,  Papilla;  enlarged; 
9,  Mandible-X-Busk's  organ,  use  unknown;  10,  Mouth  parts  of  young  tick.  (After  Osborn, 
from  Curtice;  Bull.  No.  5,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agr.). 


148  PARASITES  OF  THE  DOMESTIC  ANIMALS 

The  Cattle  Tick  in  its  Relation  to  Southern  Agriculture,  b}^  August 
Mayer.    Farmers'  Bull.  No.  261  (1906). 

Proceedings  of  a  Conference  of  Federal  and  State  Representatives 
to  Consider  Plans  for  the  Eradication  of  the  Cattle  Tick.  Bull.  No.  97 
(1907). 

Methods  of  Eradicating  Cattle  Ticks,  by  Louis  A.  Klein.  Cir.  No. 
110  (1907). 

Studies  on  the  Biologv  of  the  Texas-fever  Tick,  bv  H.  W.  Gravbill. 
Bull.  No.  130  (1911). 

Methods  of  Exterminating  the  Texas-fever  Tick,  by  H.  W.  Graybill. 
Farmers'  Bull.  No.  498  (1912). 

Progress  and  Prospects  of  Tick  Eradication,  by  Cooper  Curtice. 
Cir.  No.  187  (1912). 

Texas  or  Tick  Fever,  by  John  R.  Mohler.  Farmers'  Bull.  No.  569 
(1914). 

Life  History;  the  Nonparasitic  Development. — The  following  data 
as  to  the  life  histor}^  of  the  Texas-fever  tick  is  taken  from  Graybill 
(Studies  on  the  Biology  of  the  Texas-fever  Tick,  1911).  The  non- 
parasitic development  is  considered  bj^  this  author  under  five  periods, 
namely,  the  preoviposition  period,  the  oviposition  period,  the  incu- 
bation period,  the  hatching  period,  and  the  longevity  period  of  the 
larva? . 

The  period  of  preoviposition  extends  from  the  time  the  female  tick 
drops  until  she  begins  to  deposit  her  eggs.  In  a  series  of  investigations 
carried  out  at  Auburn,  Ala.,  m  1907-8  it  was  observed  that  the  average 
duration  of  this  period  ranged  from  three  to  forty-nine  and  three-tenths 
daj^s,  depending  largely  upon  temperature,  the  shorter  average  period 
occurring  in  August,  the  longer  in  December. 

The  average  oviposition  or  egg-Iaymg  period  for  different  months  of 
the  year  ranged  from  eight  and  three-tenths  daj^s  for  June  to  one  hun- 
dred and  twenty-seven  and  five-tenths  daj^s  for  November.  The 
maximum  period  noted  was  one  hundred  and  fift^^-two  days,  observed 
in  November,  and  the  mmimum  three  days,  observed  in  June.  The 
maximum  number  of  eggs  deposited  by  a  female  tick  was  5105,  minimum 
357,  with  an  average  ranging  from  1811  to  4089. 

The  incubation  period  was  found  to  range  from  nineteen  days  in  the 
summer  to  one  hundred  and  eighty  days  beginning  in  the  fall.  The 
conditions  essential  to  development  and  hatching  are  moisture,  such  as 
supplied  bj^  sufficient  atmospheric  humidity  to  prevent  eggs  losmg 
moisture  by  evaporation,  and  a  favorable  temperature. 

The  hatching  period  is  taken  as  the  time  required  for  all  of  the  eggs  to 
hatch  after  hatching  begins,  the  eggs  deposited  by  a  female  hatching 
approximately  in  the  sequence  in  which  the,y  are  laid.  The  average 
period  was  found  to  range  from  ten  and  six-tenths  days  for  Jul.v  to 


THE  TICKS 


149 


thirty-six  days  for  Octoljer.    The  maximum  period  observed  was  forty- 
nine  da^'s  for  October,  the  minimum  four  days  for  July. 

The  longevity  period  is  stated  to  depend  on  individual  vitahty, 
humidity,  and  temperature.  It  was  noted,  especially  in  eggs  laid  during 
the  winter,  that  some  larvse  do  not  have  sufficient  vitality  to  disengage 
themselves  from  the  eggshell  and  die  partly  inclosed  within  it ;  also  that 
others  die  veiy  soon  after  emerging.  Cold,  it  is  stated,  prolongs  longev- 
ity because  of  the  fact  that  the  tick  remains  quiescent  with  resulting 
conservation  of  bod.y  fluids  and  nourishment.  The  fact  that  the  larvae 
respond  negatively  to  light  is  an  additional  factor  promoting  longevity. 
In  places  exposed  to  the  sun  they  collect  on  the  under  side  of  leaves  and 
other  vegetation,  thus  protecting  themselves  from  loss  of  bodj^  moisture 
through  the  direct  heat  of  the  sun.  In  observations  made  it  was  deter- 
mined that  the  average  maximum  longevity  for  larvae  hatched  from  a 
number  of  lots  of  eggs  in  July  was  thirtj'-eight  and  six-tenths  days. 
From  eggs  hatched  in  October  the  average  maximum  period  was  one 
hundred  and  sixty-seven  and  four-tenths  days.  The  shortest  period 
was  four  days  for  larvae  hatched  in  July,  the  longest  two  hundred  and 
thirty-four  daA'S  for  larvae  hatched  in  October. 

The  following  summary'  is  given  of  the  data  on  the  nonparasitic 
period : 

Total  Time  from  Dropping  of  Female  until  all  Resulting  Larvce  are  Dead 


Date  engorged 

females  were 

collected 

Number 

of  engorged 

females 

Range  of 
entire- 
time 
periods 

Average 

of 
periods 

Date  engorged 

females  u-ere 

collected 

Number 

of  engorged 

females 

Range  of 
entire- 
time 
periods 

Average 
periods 

June  1,  1907 

7 

Days 
79-100 

Days 

86.9 

101 
199.6 
250.7 
279.6 

Dec.  29, 1907, 

to 
Jan.  1,  1908 

3 

Days 
181-207 

Days 
196.3 

July  1,  1907 

7 

82-112 

Jan.  29  to 
Feb.  4,  1908 

7 

156^189 

173.1 

Aug.  1,  1907 

7 

172-221 

Feb.  27  to  28, 
1908 

2 

143-162 

152.1 

Aug.  31,  1907 

6 

230-272 

Mar.  26  to 
29,  1908 

9 

144-161 

152.1 

Oct.  1,  1907 

7 

276-288 

April  29, 
1908 

14 

122-173 

142.8 

Nov.  1,  1907 

7 

200-253 

232.7 

Nov.  30, 1907 

3 

187-249 

217 

The  Parasitic  Development. — The  parasitic  development  has  three 
stages,  the  larval,  the  nyniphal,  and  the  adult.    In  the  experiments  car- 


150 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


ried  on  upon  this  portion  of  the  tick's  life  history  tick-free  animals  were 
infested  at  nine  different  times  from  July,  1907,  to  May,  1908.  It  was 
found  that  the  minimum  larval  period  ranged  from  five  to  seven  days; 
the  minimum  nymphal  period  of  females,  nine  to  eleven  days;  the  adult 
period,  from  a  minimum  of  five  to  a  maximum  of  thirty-three  days. 
The  table  which  follows  is  given  to  show  the  range  of  the  periods  ob- 
served upon  larvae  which  were  marked  after  they  had  become  attached 
and  then  kept  under  observation  from  day  to  day. 


Le7igth  of  Period  and  Total  Duration 

of  Parasitic  Development 

Date  larvce  applied 

Sex 

Length 

of  larval 

period 

Length 

of  nymphal 

period 

Length 

of  adult 

period 

Duration 

of  parasitic 

period 

1908 
Feb  29 

Females 

iT 

Days 
10-15 

Days 
5-13 

Days 
25-34 

Do 

Males 

7-9 

8-10 

- 

Do 

(?) 

7-14 

- 

- 

_ 

April  4 

Females 

7 

9-14 

4-9 

25-26 

Do 

Males 

7 

8-12 

- 

— 

May  23 

Females 

6-7 

9-12 

6-9 

22-25 

Do 

Males 

5-8 

8-13 

— 

_ 

As  to  the  importance  of  the  foregoing  data,  Graybill  says:  ''The  dura- 
tion of  each  of  these  stages  and  the  duration  of  a  single  infestation  upon 
cattle  during  different  portions  of  the  year  are  of  great  practical  im- 
portance. Upon  the  duration  of  an  infestation  depends  the  time  anmials 
must  be  kept  on  tick-free  fields  in  order  to  become  free  from  the  ticks." 


THE  TICKS  151 

Life  Histories  of  the  Dog  Tick  and  Texas-Fever  Tick  Compared 
IN  Tabular  Review  (note  italics) 

dermacentor  variabilis 
Ovigerous  Female.— Engorges  upon  host,  drops  to  ground, 
I  and  deposits  eggs. 

Eggs. — Deposited  upon  ground  in  mass. 

I 
Larvae. — Bunched  upon  grass  from  which  the}^  reach 

I  first  host. 

First  Molt,  Larvae  to  Nymphs.— ?7joon  ground,  after  drop- 

I  ping  from  first  host. 

Nymphs. — Crawl  from  grass  upon  second  host. 

Second  Molt,  Nymphs  to  Adults.— ?7?j0/i    ground,    after 
I  dropping  from    sec- 

I  ond  host. 

Males  and  Females.— Crawl  from  grass  upon  third  host; 
I  mate. 

Ovigerous  Females. — Engorge  upon  host. 

Ovigerous  Females.— Drop    to   ground    and   deposit 
eggs. 

MARGAROPUS   ANNULATUS 

Ovigerous  Female.— Engorges  upon  host,  drops  to  ground. 
I  and  deposits  eggs. 

Eggs. — Deposited  upon  ground  in  mass. 

Larvae. — Bunched  upon  grass  from  which  they  reach 
I  host. 

First  Molt,  Larvae  to  Nymphs. — Upon  host. 

Second  Molt,  Nymphs  to  Adults. 
Males  and  Females. — Upon  host;  mate. 

Ovigerous  Females. — Engorge  upon  host, 

Ovigerous  Females. — Drop    to   ground   and    deposit 
eggs. 

Loss  Occasioned  by  Cattle  Ticks.— According  to  estimates  published 
in  1914,  the  main  sources  of  loss  occasioned  by  the  cattle  tick  may  be 
summarized  as  follows: 


1.52  PARASITES  OF  THE  DOMESTIC  ANIMALS 

The  parasitic  life  of  the  ticks,  together  with  the  blood-destroying 
properties  of  the  protozoan  parasites  with  which  they  inoculate  their 
hosts,  causes  a  loss  of  flesh  and  lack  of  development  in  southern  cattle 
conservatively  estimated  at  $23,250,000. 

The  lower  price  which  southern  cattle  from  infested  districts  bring 
in  northern  stockyards  averages  at  least  $1.50  per  head.  It  is  estimated 
that  the  loss  upon  animals  marketed  under  these  conditions,  including 
stock,  beef,  and  dairy  cattle,  will  sum  up  to  $1,057,500  annually. 

The  shrinkage  in  milk  production  of  cattle  infested  with  many  ticks 
will  average  about  one  quart  per  day.  Upon  an  estimate  of  875,000 
ticky  dairy  cattle  out  of  more  than  4,000,000  dairy  cattle  below  the 
quarantine  line,  the  loss  thus  occasioned,  reckoned  at  three  cents  per 
quart,  would  amount  to  $26,250  per  day,  or,  counting  three  hundred 
milking  days  for  each  cow  to  the  year,  $7,875,000  annually. 

The  loss  among  nonimmune  southern  cattle  in  tick-free  pastures- 
through  contracting  Texas-fever  when  exposed  to  the  tick  has  been 
estimated  at  $5,812,500  per  annum. 

The  deaths  from  Texas-fever  of  pure-bred  or  high-grade  cattle  im- 
ported from  the  North  for  breeding  purposes  amount  to  about  sixty 
per  cent,  among  such  cattle  which  have  not  been  immunized  by  blood 
inoculations,  and  to  about  ten  per  cent,  among  those  which  have  had 
such  immunization.  Since  these  are  usually  expensive  animals,  the 
loss  in  such  cases  is  often  excessive. 

Considering  additional  losses,  direct  or  indirect,  as  published  by  the 
United  States  Department  of  Agriculture  in  1914,  it  will  be  found  that 
the  Texas-fever  tick  is  responsible  for  a  loss  of  about  $40,000,000  an- 
nually, in  addition  to  which  it  is  responsible  for  lowering  the  assets  of 
the  infested  country  to  the  extent  of  $23,250,000. 

Progress  in  Eradication. — Methods  of  dipping  and  pasture  rotation 
for  the  control  of  the  cattle  tick  have  been  fully  set  forth  in  bulletins 
and  circulars  published  by  the  United  States  Department  of  Agriculture 
(Farmers'  Bull.  No.  498).  These  are  freely  available  to  all  interested  in 
details  of  the  subject  which  need  not  be  repeated  upon  these  pages. 

Eradicative  measures  carried  on  by  the  Federal  Government  in 
cooperation  with  the  states  affected  by  the  cattle  tick  have  seen  in 
progress  since  1906.  Up  to  1911  twenty  per  cent,  of  the  infested  area, 
mostly  along  the  northern  boundary,  had  been  cleaned  through  this- 
systematic  cooperative  work.  At  the.  present  time  (1918),  through  the 
continuation  of  this  work,  fifty-two  per  cent,  of  the  tick-infested  area 
has  been  released  from  quarantine,  and  it  is  authoritatively  predicted 
that  five  years  hence  the  cattle  tick  will  be  entirely  eradicated  from  the 
South. 


THE  TICKS  d 

Order  II.  Lixguatulida 


15S 


Arachnida  (p.  94). — The  iiiombers  of  this  group  are  arachnids  which 
have  become  extremely  altered  in  consequence  of  their  parasitic  mode 
of  life.  Due  to  their  worm-like  body  and  endoparasitic  habits,  they  were 
formerly  placed  with  the  helminths. 

The  body  is  elongated,  annulated,  and  somewhat  flattened.  The 
bodj'  regions  are  not  defined  from  each  other.  With  the  exception  of 
two  pairs  of  articulated  hooks 
surromiding  the  mouth,  re- 
garded by  some  as  vestigial 
legs,  the  adult  body  is  entirely 
without  appendages  (Fig.  83). 

The  mouth  is  anterior,  and 
the  intestine  passes  directly 
through  the  body,  opening  by 
the  posterior  anus. 

There  are  no  circulatory  or  respiratory  organs 
general  surface  of  the  bod.y. 

The  nervous  system  is  reduced,  consisting  of  the  esophageal  ring, 
which  gives  off  filaments  to  the  cephalothorax  region.    Eyes  are  absent. 

The  sexes  are  separate;  the  male  much  smaller  than  the  female.  From 
the  eggs  there  hatches  an  ovoid  embr^'o,  constricted  at  its  posterior 
extremity,  and  provided  with  two  pairs  of  jointed  legs.  Anteriorly  it 
has  a  perforating  apparatus  by  means  of  which  it  bores  through  the 
intestinal  wall  of  its  host  and  reaches  the  liver,  or  other  organ,  in  which 
it  becomes  encysted. 

The  adult  Linguatula  (L.  rhinaria)  infests  the  nasal  cavities  of  mam- 
mals, usually  the  dog.  The  larvae  infest  the  visceral  organs  of  herbivor- 
ous animals. 


Fig  83. — Linguatula  rhinaria,  adult  (after 
Osborn,  from  Packard;  Bull.  No.  5,  Bureau  of 
Entoniologj-,  U.  S.  Dept.  of  Agr.). 


Respiration  is  by  the 


PART   II 
THE   INTERNAL   PARASITES 

CHAPTER  XIV 

PHYLUM  11.     PLATYHELMINTHES.     THE   FLUKES  AND 
TAPEWORMS 

With  but  few  exceptions  all  of  the  metazoan  internal  parasites  come 
into  the  old  division  \>rmes,  which  brings  together  animals  generally 
worm-like,  though  widely  differing  in  many  respects.  Compared  thus 
as  a  whole  with  animals  usually  rated  below  them  in  the  zoological 
scale,  .worms  are  readih'  distinguished  in  possessing  differentiated 
anterior  and  posterior  extremities,  the  anterior  directed  toward  their 
forward  movement  and  involving  a  head  which  contains  a  ganglionic 
mass  of  nerve  cells  or,  as  it  ma}'  be  called,  a  rudimentary  brain.  Fur- 
thermore, the  body  is  bilaterally  similar,  and  there  is  a  dorsal  and 
ventral  surface.  The  annulated  worms,  which  include  the  higher 
representatives,  differ  from  the  Arthropoda  mainly  in  the  absence  of 
articulated  appendages  to  their  body-segments,  while  the  lack  of  a 
notochord  and  gill-slits  distinguishes  them  from  certain  lowly  members 
of  the  Chordata.  Beyond  these  few  points  there  is  little  to  be  said  as 
to  the  characteristics  of  the  worms  considered  as  a  whole. 

The  including  in  a  single  phylum  of  all  invertebrates  generally  elongate 
and  without  articulated  appendages  is  systematically  faulty  in  that  it 
brings  together  animals  with  structural  differences  of  grand  division 
importance,  though  agreeing  in  an  external  form  generally  worm-like. 
In  most  of  the  present-day  systems  of  classification  the  worms  are  dis- 
tributed into  three,  or  at  least  two,  phyla,  the  older  class  division 
Platyhelminthes,  or  flat  worms,  being  given  grand  division  distinction. 
Many  authors  also  place  the  smooth-bodied  Nemathelminthes  and  the 
annulated  worms  in  separate  phyla,  while  another  division, — the 
Molluscoidea,  has  been  created  to  dispose  of  the  more  or  less  related 
moss-like  Pol^'zoa  (Bryozoa)  and  the  mollusc-like  Brachiopoda.  An 
objection  to  such  arrangement  is  that  groups  poor  in  species,  some  of 
them  mainh'  of  parasitic  interest,  are  placed  on  the  same  basis  as  such 
large  and  very  important  divisions  as  the  chordates  and  arthropods, 
thus  giving  them  an  undue  prominence  in  a  general  consideration  of  the 
animal  kingdom. 


156  PARASITES  OF  THE  DOMESTIC  ANIMALS 

The  classification  adopted  here  places  the  smooth  roundworms  and 
the  annulated  worms  together  in  the  phylum  Ccelhelminthes,  an  ar- 
rangement based  upon  the  presence  of  a  coelom  or  bod}^  cavity,  which 
is  a  structural  feature  clearly  defuiing  these  worms  from  the  Platyhel- 
minthes  and  establishing  a  relationship  between  the  smooth  round  and 
annulated  forms  of  primary  importance. 

The  Platyhelminthes  includes  worms  which  are  flattened  dorsoven- 
trally,  the  two  surfaces  uniting  in  more  or  less  sharp  margins.  There  is 
no  body  cavity,  the  various  organs  being  embedded  in  a  mass  of  con- 
nective tissue  and  muscle  fibers.  The  aHmentary  tract  is  a  simple  or 
bifurcated,  sometimes  branching,  pouch  having  no  anal  opening  (Fig.  85), 
the  inouth  serving  as  both  inlet  and  vent.  In  some  parasitic 
forms  (t|ipeworms)  alimentary  organs  are  entirely  wanting. 
A  true  circulatory  system  is  absent.  There  is  a  series  of  ex- 
cretory tubes  which  ramify  throughout  the  body,  usually 
opening  to  the  outside  near  the  posterior  extremity.  The 
nervous  system  consists  of  ganglia  located  above  the  esoph- 
agus, where  this  is  present,  and  the  lateral  nerves  which  these 
give  off.  Most  all  are  hermaphroditic,  the  sexual  organs 
being  distributed  over  a  large  portion  of  the  body. 

As  is  true  of  the  worms  in  general,  free  living  forms  are 
found  in  fresh  and  salt  water.  They  may  often  be  revealed 
clinging  to  the  under  side  of  rocks  (planaria.  Fig.  84)  and 
upon  the  moist  soil,  some  of  these  specimens  being  nearly 
transparent.  The  largest  members  of  the  division  are  the  tapeworms. 
^^'hich  may  reach  a  length  of  thirty  feet  or  more. 

The  phylum  contains  two  parasitic  classes,  as  follows: 
Class    I.  Trematoda. — The  flukes. 
Class  II.  Cestoda. — The  tapeworms. 

Class  I.  Trematoda 

Platyhelminthes  (p.  156). — All  of  the  members  of  this  group  are 
parasitic,  living  either  as  ecto-  or  entoparasites.  The  body  is  usually 
leaf-like,  often  much  like  a  pumpkin  seed  in  form  (Fig.  87),  and  is  pro- 
vided anteriorly  with  suckers  by  which  attachment  is  made  to  the  host. 
In  most  of  those  entoparasitic  (Distomese)  two  suckers  are  present,  one 
anterior  and  surrounding  the  mouth,  and  a  second  larger  one  just 
posterior  to  the  mouth  on  the  mid-ventral  line.  In  the  ectoparasitic 
species  (Polystomese),  which  are  usually  parasitic  upon  the  gills  and 
skin  of  aquatic  animals,  the  suckers  are  more  numerous. 

The  alimentary  tract  leads  by  a  short  gullet  to  a  bifurcation,  forming 
two  elongated  blind  sacs  which  may  or  may  not  give  rise  to  lateral 
secondary  pouches  (Fig.  85).  Eye  spots  occur  in  some  of  the  ectopara- 
sitic species  and  in  the  larvae  of  the  entoparasitic. 


PLATYHELMINTHES 


157 


Most  of  the  Trematoda  are  hermaphroditic.  At  maturity  the  sexual 
organs  reach  a  high  degree  of  development  adaptive  to  the  mode  of 
parasitism  (Introduction,  p.  5).  The  male  sexual  organs  consist  of 
tube-like  testes,  from  which  spermatic  ducts  take  origin.  These  unite 
in  a  large  seminal  vesicle,  the  terminal  portion  of 
which  is  usually  inclosed  in  a  pouch.  The  ovary 
is  also  branching  and  tube-like.  With  the  oviduct 
there  unite  ducts  from  the  vitellaria  or  yolk-glands, 
this  union  being  followed  bj'  the  much  convoluted 
uterus  which  receives  the  eggs  and  terminates  by 
the  side  of  the  male  sexual  opening  (Fig.  86). 

The  entoparasitic  trematodes  undergo  a  compli- 
cated life  histor}',  invohang  alternation  of  hosts 
and,  within  the  intermediate  host,  multiplicative 
generations.  A  typical  example  of  this  cycle  is 
given  further  on  in  reference  to  the  species  Fasciola 
hepatica. 

Most  of  the  trematode  parasites  of  mammals 
live  in  the  liver,  producing  the  affection  known  as 
hepatic  fascioliasis  (distomiasis),  or  commonly  as 
liver  rot.  Others  invade  the  blood,  lungs,  and 
stomach,  causing,  accordingly,  vascular,  pulmonary, 
and  gastric  fascioliasis.  The  latter  forms  are  rarely 
met  with  in  the  United  States. 

The  species  to  be  considered  come  imder  three 
families,  as  follows: 

Famih'    I.  Fasciolidae. — The  common  liver  flukes. 

Family   II.  Amphistomidse. — Of  the  rumen. 

Familv  III.  Schistosomidae. — The  blood  fluke. 


Fig.  So.— Sketch  of 
Fasciola  hepatica, 
showing  bifurcated  and 
branching  alimentary 
tract:  si,  mouth  and 
anterior  sucker;  s2, 
posterior  sucker;  t.  a., 
alimentary  tract, — en- 
larged (after  Boas,  by 
Kirkaldy  and  Pollard, 
from  Thomas). 


Classification   of   Parasites   of   the    Phylum    Pl.\tyhelmixthes 

Phylum  II.  Platyhelminthes.    P.  155. 
Class  A.  Trematoda.    Flukes.    P.  156. 
Order  1.  Distomese.    P.  156. 
Family  (a)  Fasciolidae.    P.  160. 
Genus  and  Species: 

Fasciola  hepatica.    Hosts,  sheep,  cattle,  etc.    P.  160. 
Dicroca^lium  lanceatum.    Hosts,  same.    P.  160. 
Fasciola  americanus.    Hosts,  same.    P.  160. 
Family  (b)  Schistosomidae.    P.  168. 
Genus  and  Species: 

Schistosoma  bovis.    Ho.sts,  cattle,  sheep.    P.  168. 
Family  (c)  Amphistomidse.    P.  167. 


1.58  PARASITES  OF  THE  DOMESTIC  ANIMALS 


Fig.  83. — Reproductive  organs  of  liver  fluke:  f,  female  aperature;  s.  v.,  seminal  \'esicle 
y.  g.  1.,  diffuse  yolk  glands;  sh.  g.,  shell  gland;  v.  d.,  vas  deferens;  T.,  testes;  ov,  ovary 
(dark);  ut,  uterus;  c.  s.,  cirrus  sac;  p,  penis;  m,  mouth;  g,  anterior  lobes  of  gut  (after 
Thomson,  from  Sommer). 


PLATYHELMINTHES  •  159 

Genus  an(J  Species: 

Ainphistomiim  cervi.    Hosts,  niniinants.    P.  167. 
Class  B.  Cestoda.    Tapeworms.    P.  169. 
Order  1.  Polyzoa. 

Family  (a)  Taeniidae.    P.  170. 
Genus  and  Species: 

Anoplocephala  perfoliata.    Host,  equines.    P.  174. 

A.  mamillana.    Host,  equines.    P.  175. 

A.  plicata.    Host,  equines.    P.  175. 

Moniezia  expansa.    Hosts,  cattle,  sheep,  goats.    P.  176. 

M.  alba.    Hosts,  same.    P.  176. 

M.  planissima.    Hosts,  same.    P.  176. 

Thysanosoma  actinioides.    Host,  sheep.    P.  176. 

Dipyhdium  caninum.    Hosts,  dog,  cat,  man.    P.  178. 

Larva,    Cryptocystis    trichodectes.      Hosts,    flea,    louse. 
P.  178. 
Taenia  hj-datigena.    Host,  dog.    P.  178. 

Larva,    Cysticercus   tenuicollis.      Hosts,    ruminants   and 
hogs.    P.  179. 
T.  pisiformis.    Host,  dog.    P.  179. 

Larva,   Cysticercus  pisiformis.     Host,  ral)])it.     P.  179. 
T.  ovis.    Host,  dog.    P.  204. 

Larva,  Cysticercus  ovis.    Host,  sheep.    P.  203. 
Multiceps  multiceps.    Host,  dog.    P.  179. 

Larva,  Multiceps  nuilticeps.    Host,  Herbivora.    P.  179. 
M.  serialis.    Host,  dog.    P.  179. 

Larva,    Multiceps    serialis.      Hosts,    rabbit    and    other 
rodents.    P.  180. 
M.  gaigeri.    Host,  dog.    P.  181. 

Larva,  Multiceps  gaigeri.    Host,  ruminants.    P.  181. 
Echinococcus  granulosus.    Hosts,  dog,  cat.    P.  181. 

Larva,  Echinococcus  granulosus.    Hosts,  riuninants,  hog, 
etc.    P.  181. 
Taenia  taeniaeformis.    Host,  cat.    P.  184. 

Larva,  Cysticercus  fasciolaris.    Hosts,  rat,  mouse.   P.  184. 
Cittotaenia  denticulata.    Host,  chicken.    P.  185. 
Choanota^nia  infundibuliformis.    Host,  chicken.    P.  189. 

Larva,  a  cysticercoid.    Host,  house  fly.      P.  189. 
HjTiienolepis  carioca.    Host,  chicken.    P.  190. 
Davainea  tetragona.    Host,  chicken.    P.  190. 
D.  cesticillus.    Host,  chicken.    P.  190. 
D.  echinobothrida.    Host,  chicken.    P.  191. 
D.  proglottina.    Host,  chick(>n.    P.  191. 
Larva,  a  cvsticercoid.    Host,  snail.     P.  191. 


160  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Taenia  saginata.    Host,  man.    P.  195. 

Larva,  Cysticercus  bovis.     Host,  ox.     P.  195. 
T.  solium.    Host,  man.    P.  199. 

Larva,  Cysticercus  cellulosse.     Host,  hog,  etc.     P.  199. 
Family  (b)  Diphyllobothriidse.    P.  185. 
Genus  and  Species: 

Diphyllobothrium  latum.     Hosts,  man,  dog,  cat.     P.  185. 
Larva,  a  plerocercoid.    Host,  fish.    P.  185. 


Family  I.  Fasciolid^ 

1.  Fasciola    hepatica   (Distomum    hepaticum).     The    Liver  Fluke 

(Fig.  87).  Trematoda  (p.  156). — ^The  body  is  flattened,  pale  brown  in 
color,  oval  in  shape,  and  broadest  in  front,  where  it  is  terminated  by 
a  conical  process  bearing  at  its  apex  the  oral  sucker  which  surrounds 
the  mouth.  A  larger  ventral  sucker  is  situated  about  3  mm.  behind 
the  oral.  The  cuticle  is  studded  with  minute  spines  directed  back- 
ward. The  bifurcations  of  the  ahmentary  tract  have  ramifying 
branches.  The  vulva  is  situated  beside  the  male  opening  or  a  little 
behind  it. 

Length,  20-30  mm.  {%-\H  inches);  width,  10-13  mm.  (73-3^  an 
inch). 

The  eggs  are  brown  or  greenish-yellow,  provided  with  an  operculum 
a,t  one  end.    They  are  oval  and  130-145  microns  in  length. 

2.  Dicrocoelium  lanceatum  (Fasciola  lanceolata).  The  Small  Liver 
Fluke  (Fig.  87).  Trematoda  (p.  156).— The  body  is  slender  and 
lancet-shaped,  mottled  brown  by  contained  ova.  The  integument  is 
smooth  and  semi-transparent.  The  intestine  has  two  nonramifying 
branches. 

Length,  4-9  mm.  (3/16-3/8  of  an  inch);  width,  2.5  mm.  (1/8  of  an 
inch) . 

The  eggs  are  oval,  brownish  in  color,  37-40  microns  in  length,  and 
provided  with  an  operculum. 

3.  Fasciola  magna  (F.  americana,  Distomum  americanum,  D.  mag- 
num). The  Large  American  Liver  Fluke  (Fig.  87).  Trematoda 
(p.  156). — Similar  to  F.  hepatica,  but  larger,  measuring  25-33  mm. 
(1-13^  inches)  in  length  and  12-17  mm.  (J^-^)  of  an  inch  in 
width. 

Life  History  of  Fasciola  hepatica. — The  eggs  leave  the  uterus  be- 
fore the  beginning  of  embryonic  development  and  pass  to  the  outer 
world  by  way  of  the  bile  ducts  and  intestines.  In  heavy  infestation 
enormous  numbers  may  be  passed  by  a  single  host  animal,  one  mature 
fluke  producing  in  the  neighborhood  of  one  hundred  thousand  eggs. 


PLATYHELMINTHES  161 

After  a  period  of  embryonal  development,  which  will  only  occur  pro- 
viding the  eggs  have  reached  water  and  suitable  conditions  of  tempera- 
ture, the  larva  escapes  by  the  lifting  of  the  operculum  of  the  shell.  It 
is  then  in  the  stage  of  the  miracidium  (Fig.  88,  2),  an  infusorian-like 
organism,  cihated,  elongated,  broader  in  front,  and  about  130  microns  in 
length.  During  its  free-swimming  period  it  must  meet  with  a  suitable 
host  within  a  few  hours  or  it  will  perish.  This  host  is  a  small  snail, 
usually  of  the  genus  Limnjea  (L. 
humilis)  into  which  the  larva 
bores  its  way  by  a  perforating 
rostrum  at  its  anterior  extremity. 
If  it  escapes  its  aquatic  enemies 
during  this  free  stage  and  arrives 
at  a  suitable  location  within  the 
snail,  usually  the  pulmonary 
chamber,  the  larva  loses  its  cilia 
and  digestive  tube  and  becomes 
transformed  into  a  sporocyst  (Fig.       yig.  87.-Left  to  right,  Fascioia  hepatica, 

88,  3) — a  sort  of  reproductive  sac,     F.     americanus,     Dicroccelium     lanccatum; 

ovoid  in   form   and   acquiring  a    l^^^lf  ^'^^  ^'^'■''^^^""  ^'""^  ^"*^°'"'^  ^p^"" 
length  of  about  0.5-0.7  mm.    The 

cyst  now  becomes  filled  with  germ-cells  which  are  disposed  in  masses 
(morula)  ordinarih'  five  to  eight  in  number. 

The  masses  of  germ-cells  become  transformed  into  so  manj-  redice 
(Fig.  88,  5  and  6)  which  may  be  seen  in  different  stages  within  the  cyst. 
The  rediae  are  cylindrical  in  form  and  have  a  simple  intestine  and 
pharynx  with  lips  turned  out  like  a  sucker.  When  they  have  attained 
a  certain  stage  of  development  the  rediae  become  actively  motile,  finally 
rupturing  the  maternal  cyst  and  passing  to  another  organ  of  the  snail, 
usually  the  liver,  in  which  location  Xhey  grow  to  a  length  of  1.3-1.6  mm. 
Within  the  body  of  the  redia  are  germ-cells  formed  into  six  to  ten  cellular 
masses  which  are  to  be  transformed  into  so  many  daughter  rediae,  or 
directly  into  fifteen  to  twenty  cercarice  (Fig.  88,  7).  Both  daughter 
rediae  and  cercariae  leave  the  mother  redia  by  a  birth-opening  located 
anteriorly. 

The  developed  cercaria  has  an  oral  and  ventral  sucker,  a  muscular 
pharynx,  and  a  bifurcated  intestine  which  is  as  yet  without  lateral 
branches.  It  has  a  flat  oval  body  about  0.28  mm.  in  length,  provided 
with  a  long  actively  vibratile  tail.  The  cercariae  escape  from  the  snail 
and  swim  about  energetically  ui  the  water,  eventually  finding  their  way 
to  an  aquatic  plant  or  grass  stalk.  Here  the  tail  is  lost  and  the  cystoge- 
nous  cells  of  the  body  form  a  mucoid  substance  which  serves  both  to 
encyst  the  cercariae  and  to  attach  them  to  the  grass.  The  cysts  may  be 
observed  upon  the  specimens  of  vegetation  as  little  white  points  about 


162  PARASITES  OF  THE  DOMESTIC  ANIMALS 


the  size  of  an  ordinary  pin-head.    An  encysted  cercaria  will  remain  alive 
for  an  extended  period  as  long  as  the  grass  upon  which  it  is  lodged  is 


Fig.  88. — Life  history  of  liver  fluke:  1,  egg  containing  de- 
veloping embryo;  2,  free  swimming  miracidium;  3,  sporocyst; 
3a,  snail  of  the  genus  Limnaea;  4,  division  of  sporocyst; 
5,  sporocyst  containing  developing  redise;  6,  redia  with  cer- 
carise  or  more  redise  developing  within  it;  7,  cercaria;  8,  young 
fluke  (after  Thomson,  from  Thomas). 

supplied  with  moisture.     Drought  probably  destroys  it,  though  the 
length  of  time  it  may  survive  such  conditions  is  undetermined. 
When  plants  bearing  these  cysts  are  eaten  by  grazing  animals  the 


PLATYHELMINTHES  163 

cysts,  upon  reaching  the  stomach,  are  dissolved,  setting  free  the  par- 
asites which,  passing  to  the  intestine,  enter  the  bile  ducts  and  there 
become  mature.  After  laying  their  eggs  the  majority  of  the  flukes  pass 
down  the  bile  ducts  to  the  mtestine  where,  under  the  hifluence  of  the 
digestive  juices,  they  shrivel  and  die. 

The  period  of  time  occupied  ])y  the  entire  cycle  is  so  influenced  by 
climatic  conditions  that  no  definite  estimate  as  to  it  can  be  given. 
As  a  rough  approximation,  twelve  weeks  may  be  given  as  about  the 
time  required  under  such  favorable  conditions  as  usually  prevail  during 
the  summer  season. 

The  life  histories  of  Dicrocoelium  lanceatum  and  Fasciola  magna  are 
probably  essentially  similar  to  that  of  F.  hepatica,  but  are  as  yet  not 
definitelv  known. 


Tabular  Review^  of  Life  History  of  Fasciola  Hepatica 
Adult  Fluke. — In  bile  duct  of  liver  of  rmninant. 

I 
Egg.— Free. 

I    . 
^liracidium. — Free. 

I 
Sporocyst. — In  puhnonarj'  chamber  of  snail. 

I  ^1 

Sporocysts    5  to  8  Redise. 

[      I 
Redise. — In  liver  or  other  organ  of  snail. 

Daughter  Rediae     15  to  20  Cercarise 

Cercarise. — Free. 


I 
Cvsts. — Upon  grass  stalks  or  other  vegetation. 

Adult  Flukes. — In  bile  duct  of  Uver  of  ruminants  after 
ingestion  of  c^'sts. 

Prevalence. — The  loss  from  hepatic  fascioliasis  in  England  was  for 
a  time  in  the  neighborhood  of  three  million  head  of  sheep  annually. 
It  was  principally  for  this  reason  that  investigations  were  made  by 
which  the  life  history  of  the  parasite  was  determined,  and  by  which 
was  revealed  the  essential  alternation  between  the  sheep  and  snail 
host.  This  pointed  the  way  for  measures  of  control  consisting  mainly 
in  the  elimination  of  snails  by  the  drainage  of  pastures  or  in  the  limiting 


164  PARASITES  OF  THE  DOMESTIC  ANIMALS 

of  the  sheep  to  pastures  free  from  standmg  water  or  overflow.  Since 
the  adoption  of  such  preventive  measures  the  loss  from  this  source  in 
England  and  other  European  countries  has  been  greatly  reduced. 

While  fascioKasis  has  not  been  as  prevalent  in  the  United  States  as  in 
Europe,  there  are  a  sufficient  number  of  cases  to  demonstrate  the  pos- 
sibility of  its  becoming  so  unless  such  precautions  are  taken  as  are  in- 
dicated by  the  life  historj^  of  the  fluke.  Probably  the  freedom  from  such 
destructive  prevalence  has  been  largely  due  to  the  fact  that  in  this 
countrj',  more  generally  than  in  Europe,  it  is  the  practice  to  turn  sheep 
upon  higher  and  diyer  pasturage. 

The  three  species  of  flukes  which  have  been  mentioned  mfest  the 
liver,  therefore  the  hepatic  form  of  fascioliasis  is  the  most  important. 
As  would  be  concluded  from  the  mode  of  infection,  herbivorous  animals 
are  most  often  affected,  those  which  crop  the  grass  close  to  the  ground, 
as  sheep  and  goats,  being  for  this  reason  especially  susceptible.  Horses, 
swine,  Carnivora,  and  even  man  may  be  invaded  incidentally  by  flukes, 
though  in  such  cases  they  are  rarely  present  in  such  numbers  as  to  produce 
perceptible  disturbance.  The  giant  fluke  {Fasciola  magna)  is  most  often 
found  in  the  liver  of  deer  or  cattle  in  the  Southwestern  portion  of  the 
United  States.  It  is  supposed  to  be  a  species  native  to  wild  rummants 
before  the  introduction  into  this  country  of  those  in  domestication. 

Infection. — While  infestation  of  sheep  most  frequently  occurs  from 
the  ingestion  of  plants  upon  which  the  encysted  cercarise  are  attached, 
water  contaminated  with  detached  cercariae  may  infect  directly,  or  by 
vegetation  over  which  it  has  washed.  It  is  probable  that  many  cases 
in  cattle  in  the  United  States  result  from  the  introduction  of  the  flukes 
by  the  latter  means.  Cattle  are  not  as  close  grazers  as  sheep,  but  the}- 
drink  more  frequently,  often  from  shallow  collections  of  water  which 
may  contain  larvae  derived  from  the  excrement  of  sheep  or  rabbits. 

As  many  encj^sted  cercariae  survive  the  frosts  even  of  the  late  fall, 
the  season  during  which  infection  may  take  place  is  somewhat  extended, 
some  investigators  claiming  that  it  may  occur  at  any  time  of  the  year. 
However,  warmth  being  highly  favorable  to  the  development  of  the  ova, 
it  is  essentially  during  the  summer  and  early  autumn  that  animals  are 
most  likely  to  become  invaded.  It  is  obvious  that  the  most  numerous 
and  most  severe  cases  would  occur  in  seasons  of  copious  rainfall,  more 
elevated  pastures  at  such  times  affording  by  their  collections  of  water 
and  overflow  favorable  conditions  for  the  development  of  the  parasites. 
The  flukes  may  be  introduced  into  lands  previously  free  from  them 
by  new  stock,  or  by  wild  herbivorous  animals,  such  as  deer  and  rabbits. 
After  infestation  has  once  taken  place,  it  will,  through  successive  in- 
fections, mcrease  in  degree  the  longer  the  pasture  is  used. 

Migrations  and  Pathogenesis. — It  is  probable  that  the  migration 
of  the  parasites  from  the  small  intestine  into  and  along  the  bile  ducts 


PLATYHELMINTHES  165 

is  accomplished  by  the  extending  forward  of  the  parasite's  anterior 
end,  with  alternate  fixing  of  the  oral  and  ventral  sucker.-  The  majority 
remain  in  the  bile  ducts,  though  some  upon  reacliing  the  smaller  ducts 
break  through  and  pass  into  the  liver  tissue  where  they  msiy  excavate 
and  destroy  large  areas.  Such  migrations  may  extend  through  Ghsson's 
capsule  to  the  serous  covering  of  the  organ  and  thus  give  rise  to  per- 
itonitis in  addition  to  the  inflammation  of  the  hepatic  parenchj-ma. 
They  do  not  essentially  remain  confined  to  the  liver,  but  may  pass 
through  the  capsule  and  serosa  into  the  peritoneal  cavity.  Others  may 
reach  the  ramification  of  the  portal  vein  and  set  up  an  endophlebitis 
with  accompanying  thrombosis  and  embolism;  or  the  hepatic  veins  may 
be  involved  and  some  flukes  be  carried  by  the  blood  current  to  the 
thoracic  organs. 

The  destruction  of  liver  tissue  in  hepatic  fascioliasis  is  largely  the 
result  of  direct  irritation  due  to  the  spiny  processes  covering  the  par- 
asites. During  the  first  few  weeks  after  being  taken  up  by  the  host  the 
flukes  are  small  and  do  not  cause  a  serious  irritation.  Later  the}'  set 
up  an  acute  inflammatory  condition  of  the  bile  ducts  and  liver  tissue, 
the  hepatitis  remaining  more  or  less  localized  or  becoming  generalized 
according  to  the  number  of  parasites  present  and  the  extent  of  their 
migrations.  In  certain  cases  there  is  abscess  formation,  or  hemorrhages 
may  occur  due  to  the  breaking  down  of  the  walls  of  blood  vessels.  The 
inflammation  running  a  chronic  course  is  associated  with  connective 
tissue  prohferation,  causing  a  thickening  of  the  walls  of  the  ducts.  Later 
this  process  extends  to  the  interlobular  connective  tissue  and  brings 
about  cirrhosis  of  the  liver. 

Flukes  which  have  remained  in  the  bile  ducts  pass  back  into  the 
duodenum  soon  after  the  reproductive  function  has  been  accomplished. 
It  is  thought  by  certain  investigators  that  the  period  of  time  which 
the}'  remain  in  the  ducts  does  not  exceed  nine  to  twelve  months.  Within 
the  intestines  they  are  much  altered  b}'  the  intestinal  juices  and  pass 
from  the  host  with  the  excrement.  z 

6  -' 

Fascioll\sis  of  Sheep  ^^---^ 

Symptoms  and  Course. — An  animal  harboring  but  few  flukes  will 
give  no  evidence  of  functional  disturbance.  This  can  be  readily  dem- 
onstrated in  sheep-slaughtering  establishments  where  moderately  in- 
fested livers  have  been  repeatedly  found  in  sheep  in  prime  condition. 
In  heavier  infestations  a  developing  period  of  about  three  to  six  weeks 
intervenes  between  the  taking  up  of  the  flukes  and  the  appearance  of 
s>'mptoms. 

In  sheep  usually  the  first  s\aiiptom  to  be  noticed  is  dullness,  man- 
ifested b}'  slowness  of  movement  and  an  inclination  to  lag  behind  the 


166  PARASITES  OF  THE  DOMESTIC  ANIMALS 

flock.  On  examination  of  the  visible  mucosae  (conjunctiva)  and  inner 
surface  of  the  ears  they  will  be  found  to  be  paler  than  usual,  and  there 
ma}'  already  be  edematous  swelling  of  the  eyelids  and  under  the  brisket. 
Notwithstanding  the  anaemia,  the  general  phj'sical  condition  of  the 
animal  may  still  be  good;  there  is,  in  fact,  a  tendenc}^  to  fatten,  which 
ma}^  be  explained  phj'siologicalh'  in  the  increased  assimilation  of  the 
fat-forming  elements  of  the  food,  brought  about  by  the  stimulationim- 
parted  by  the  flukes  to  the  flow  of  bile. 

This  stage,  however,  is  soon  followed  b}-  a  marked  increase  in  dullness 
and  a  disinclination  to  take  food.  The  animal  ruminates  slowly  and 
irregularly,  the  fleece  becomes  chy  and  brittle,  and  in  places  may  loosen 
and  drop  out ;  the  skin  and  mucosae  are  whitish-yellow  in  color,  the  puffy 
conjunctiva  forming  a  prominent  ring  about  the  cornea.  Though  the 
gheep  ma}'  still  be  fat,  weakness  and  disinclination  to  resist  handling 
become  moi'e  pronounced.  With  progressiveh'  diminished  appetite, 
however,  there  is  loss  of  flesh,  and  the  edema  of  the  dependent  parts 
increases,  involving  the  lower  part  of  the  neck,  throat,  and  cheeks.  The 
presence  of  ascites  is  evinced  upon  percussion  of  the  pendulous  abdomen, 
and  the  respiration  becomes  labored  and  frequent. 

With  these  s\anptoms,  which  generalh'  appear  about  the  third  month 
after  infestation,  the  disease  is  at  its  maximum,  usually  reached  in  the 
early  winter  inonths.  The  anaemia,  edema,  and  cachexia  have  now 
become  more  pronounced ;  in  most  of  the  advanced  cases  there  is  diarrhea 
by  which  large  numbers  of  eggs  may  be  distributed  about.  Finally, 
in  a  condition  of  extreme  emaciation  and  weakness,  the  animal  dies. 

Prognosis. — ]\Iost  of  the  losses  from  fascioliasis  of  sheep  are  among 
the  lambs.  Older  animals  and  those  but  moderately  infested  gradually 
recover  with  the  passage  of  the  flukes  from  the  liver  into  the  intestine, 
this  usually  occurring  in  the  early  spring.  With  the  disappearance  of 
the  edematous  swellings  and  the  return  of  the  appetite,  the  animal  re- 
sumes a  good  physical  appearance  and  seems  to  completely  recover. 
The  hver  lesions,  however,  will  not  entirely  heal,  and,  impairing  the 
function  of  the  organ,  will  eventually  have  a  deleterious  effect  upon 
the  animal. 

,  Fascioliasis  of  Cattle 

In  cattle  fascioliasis  presents  the  same  s\'mptoms  as  in  sheep.  Due 
to  the  greater  resistance  of  these  animals,  however,  the  effects  are  much 
less  severe  and  maj^  often  pass  unperceived.  If  the  flukes  are  numerous 
there  maj^  be  digestive  disturbances  manifested  b}-  loss  of  appetite, 
diarrhea,  and  t^-mpanites;  very  rarely  there  are  edematous  swellings  in 
the  dependent  parts  of  the  body.  Fatalities  from  fascioliasis  are  rare 
among  cattle.  When  they  occur  it  is  usualh'  among  calves  which  have 
reached  an  advanced  emaciation. 


PLATYHELMIXTHES  167 


Family  II.  Amphistomid.e 

Amphistomum  cervi  {A.  conicum)  is  a  species  belonging  with  this 
family  not  infrequently  found  in  the  rumen  of  domestic  ruminants  of 
this  and  other  coimtries.  Specimens  collected  in  the  Penns3'lvania  State 
Laboratory  measure  6  to  7  mm.  (3/16  to  1/4  of  an  inch)  in  length.  The 
body  is  conical  m  form,  thick,  attenuated  anteriorh',  gradually  en- 
larging posteriorly,  the  posterior  end  being  obtuse  and  a  little  curved 
ventral ly.  The  mouth  is  terminal  and  surrounded  by  a  small  sucker. 
At  the  thickened  posterior  extremity  there  is  a  second  and  much  larger 
sucker.  The  color  is  white  or  reddish,  darker  at  the  attenuated  anterior 
portion.  Hermaphroditic;  genital  orifices  ventral  and  median,  situated 
in  the  anterior  third  of  the  body.     Its  development  is  not  known. 

This  fluke  is  a  parasite  in  the  rumen  of  the  ox  and  other  domestic 
and  wild  ruminants.  It  fixes  itself  by  means  of  its  posterior  sucker 
between  the  papillae  of  the  rumen.  Being  very  easily  overlooked  in  its 
resemblance  to  the  papillae,  it  is  quite  probable  that  it  is  more  prevalent 
than  would  appear  from  our  present  records. 

The  parasite  has  been  considered  as  inoffensive  to  the  health  of  the 
host  animal. 

Control  of  Fascioll\sis 

In  sections  where  fascioliasis  has  appeared  a  prophylactic  measure 
of  first  importance  is  the  avoidance  of  pastures  which  are  wet  or  contain 
collections  of  water  affording  habitation  for  snails.  The  following  direc- 
tions formulated  b}'  Thomas — as  stated  by  Neumann — for  limiting  the 
ravages  of  fasciohasis  are  here  quoted  m  part : 

"a.  Destroy  the  diseased  sheep  and  bury  them. 

"b.  Only  put  on  dvy  pastures  affected  sheep  intended  for  the  butcher, 
as  the  fluke  ova  they  evacuate  cannot  develop  in  the  absence  of  humidity. 

"c.  As  hares  and  rabbits — which  are  sometimes  bearers  of  distomes — 
may  infest  pastures,  they  should  not  have  access  to  those  on  which 
sheep  graze.    But  this  recommendation  cannot  well  be  carried  out. 

"d.  Drain  wet  pastures,  or,  if  this  cannot  be  accomplished,  dress 
them  with  salt  or  lime.  The  latter  in  solution — 0.75  per  cent. — will 
destroy  fluke  embryos  as  well  as  the  snails.  With  regard  to  salt,  we  are 
indebted  to  Perroncito  for  some  precise  notions  as  to  its  action.  Erco- 
lani  had  for  a  long  time  observed  that  water  slightly  impregnated  with 
salt  killed  the  cercariae,  and  in  acting  on  these  and  on  the  encysted 
larvae  of  the  Limncea  palustris.  Perroncito  found  that  in  a  2  per  cent, 
solution  these  parasites  died  in  less  than  five  minutes;  in  a  1  per  cent, 
solution  they  rolled  themselves  up  at  the  end  of  two  to  seven  mmutes, 
and  perished  after  twenty  to  thirty-five  minutes.  The  same  happened 
in  0.64  per  cent,  solutions:  and  in  those  of  0.25  per  cent,  they  were  still 


168 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


alive  after  more  than  twenty  hours.  The  period  when  salt  or  lime 
should  be  spread  on  the  pastures  should  coincide  with  the  time  when 
the  embryos  of  the  distomes  and  the  cercarise  abound — that  is,  June 
and  July  for  the  first,  and  August  for  the  second." 

If  it  is  impracticable  to  keep  sheep  from  land  upon  which  conditions 
are  favorable  for  the  development  of  flukes,  they  should  each  be  given 
in  the  morning  daily  two  drams  of  salt  mixed  with  feed.  When  possible, 
the  salt  may  also  be  given  in  their  drinking  water  in  the  proportion  of 
0.5  per  cent.  The  salt  is  fatal  to  the  ingested  cercarise  and  tends  to 
fortify  the  sheep  b}'  favoring  digestion  and  assimilation. 

Treatment. — No  effective  therapeutic  agent  for  fascioliasis  has  as 
yet  been  found.  Owing  to  the  remote  location  of  the  parasites,  it  is 
hardly  likeh'  that  anything  could  be  given  which  would  affect  them. 


BiLHAKZIOSIS 

This  name  has  been  given  to  a  disease  of  cattle  and  sheep  caused  by 
the  blood  fluke  Schistosoma  hovis  {Bilharzia  bonis;  B.  crassa)  of  the  family 
Schistosomidse. 

In  this  trematode  (Fig.  89)  there  is  presented  the  pecuharity  of  sep- 
arate sexes.  The  female,  longer  and  much  nar- 
rower than  the  male,  is  filiform,  18-20  mm.  {% 
of  an  inch)  in  length,  and  has  a  buccal  and  ven- 
tral sucker.  The  male  is  cylindrical,  about  14  mm. 
{}/2  an  inch)  in  length,  and  has  two  suckers.  It 
carries  the  female  in  a  ventral  furrow  formed  by 
the  two  sides  of  the  body  which  are  broad  and 
reflected  inward.  Both  male  and  female  genital 
apertures  are  situated  immediately  behind  the 
ventral  sucker. 

The  eggs  are  elongate,  and  at  one  pole  termi- 
nate in  a  pyriform  point.  They  pass  from  the 
host  with  the  feces  and  urine,  and,  in  the  presence 
of  water,  set  free  a  ciliated  embiyo. 

This  parasite  has  been  found  in  the  portal  and 
abdominal  veins  of  cattle  of  tropical  and  sub- 
tropical countries.  The  parasites  themselves 
seem  to  do  but  little  injury.  The  eggs,  however, 
by  their  accumulation  and  sharp  points,  may 
rupture  the  capillaries.  If  these  are  of  the 
genito-urinary  system,  the  chief  s\nnptom  is  a  bloody  urine.  Where 
the  eggs  have  accumulated  in  the  capillaries  of  the  bladder,  they  rup- 
ture these  and,  passing  through  the  mucosa,  fall  into  the  cavity  of  the 
organ.    The  resulting  cystitis  is  manifested  In'  the  hsematuria  and  the 


Fig.  89. — Schistosoma 
bovis,  male  and  female, — 
enlarged. 


PLATYHELMINTHES  169 

pain  which  accompanies  micturation.  If  the  parasites  are  contained 
in  the  veins  of  the  rectum,  there  are  similar  lesions  in  this  organ;  the 
feces  may  be  stained  with  blood,  and  there  is  a  condition  somewhat  re- 
sembling piles. 

Diagnosis  is  best  made  by  a  microscopic  examination  of  the  urine 
to  determine  the  presence  of  the  eggs  which  may  be  readily  recognized 
by  their  characteristic  elongate  shape  and  polar  termination  in  a  sharp 
point. 

As  the  lesions  are  produced  by  the  eggs,  the  severity  of  the  symptoms 
will  essentially  depend  upon  the  number  of  parasites  present.  In  the 
majority  of  cases  the  infection  is  light  and  may  give  rise  to  no  more  than 
a  slight  chronic  C3^stitis.  In  the  more  rare  cases  of  severe  infection  death 
may  ensue  from  rupture  of  the  bladder  or  from  uraemia  accompanying 
an  acute  nephritis.  A  heav}^  intestinal  infection  may  bring  about  an 
exhausting  and  fatal  dysentery. 

It  is  probable  that  infection  has  its  source  in  contaminated  drinking 
water.  Therefore,  where  bilharziosis  has  made  its  appearance,  the  water 
should,  as  a  preventive  measure,  be  filtered,  or  the  cattle  removed  to  an 
un contaminated  supply. 

Treatment  can  only  be  applied  to  the  relief  of  sjaiiptoms  as  they 
appear. 

Class  II.  Cestoda 

Platyhelminthes  (p.  156). — An  important  character  of  the  cestodes 
is  that,  as  a  result  of  their  advanced  parasitism,  they  have  lost  the  last 
trace  of  an  alimentary  canal,  and  obtain  their  nourishment  by  absorp- 
tion through  their  integument  of  the  partly  digested  food  of  the  host. 
Also  markedl}^  distinguishing  them  are  the  two  developmental  stages, — 
the  bladder  worm  (Fig.  112,  h  and  c)  and  the  mature  worm  (Fig.  107) 
with  its  sexuall}^  developed  segments,  the  first  living  usually  in  tissues, 
such  as  muscular,  liver,  nervous,  and  serous,  of  the  intermediate  host; 
the  second  in  the  alimentary  tract  of  the  definitive  host.  The  adult  is, 
in  its  general  form,  band-like,  and  consists  of  two  parts, — the  scolex 
(Fig.  109),  which  is  generally  referred  to  as  the  head,  and  a  series  of 
segments  which  are  formed  from  the  scolex  asexually  by  longitudinal 
growth  and  transverse  segmentation.  It  is  due  to  this  fact  that  an 
animal  is  not  rid  of  its  tapeworm  so  long  as  the  head  is  retained  in  the 
intestine.  As  the  segments  are  pushed  on  by  the  formation  of  younger 
segments  at  the  scolex,  they  become  progressively  wider  and  longer, 
the  width  of  the  younger  ones  usually  much  exceeding  their  length, 
while  the  oldest,  which  are  those  most  distant  from  the  scolex,  may 
become  longer  than  wide.  Each  mature  segment  is  hermaphroditic, 
the  uterus  usuall}^  containing  a  large  numl)er  of  eggs.  In  the  Taeniidae 
the  genital  pores  (sexual  openings)  are  on  the  margin  or  margins  of  the 


170  PARASITES  OF  THE  DOMESTIC  ANIMALS 

individual  segments.  In  the  Diphj'llobothriidae  they  are  on  the  flat 
ventral  surface.  The  number  of  segments  varies  from  three  or  four 
(Echinococcus  granulosus)  to  several  thousand  (Diphyllobothrium  latum), 
a  fact  which  gives  to  some  species  an  enormous  size.  In  the  head  is  a 
cerebral  ganglion  from  which  two  principal  nerves  run  backward, 
usualh'  near  the  lateral  margins  of  the  segments.  An  excretory,  or  so- 
called  water-vascular  system,  extends  through  the  whole  length  of  the 
worm  by  two  principal  trunks  which  may  be  connected  by  vessels 
running  across  the  posterior  margin  of  each  segment,  the  system  ter- 
minatmg  at  the  hinder  edge  of  the  last. 

Of  the  Cestoda,  two  families  are  to  be  described  as  containing  species 
parasitic  to  domestic  animals  and  man.    These  are  as  follows: 

Family  I.  Taeniidse. 

Family  II.  DiphyllolDothriidae. 

Family  L  T.exiid.e 

Cestoda  (p.  169). — With  rare  exception,  this  family  includes  all  of 
the  tapeworms  of  domestic  animals  and  man  in  the  United  States.  Its 
members  have  the  head  furnished  with  four  round  or  oval  cup-like 
suckers  of  muscular  structure  (Fig.  109),  which,  by  their  contraction, 
produce  a  vacuum  affording  a  close  attaclmient  to  the  intestinal  mucosa 
of  the  host.  These  suckers  may  surround  a  prominence, — the  rostellum 
(Fig.  95),  or  in  other  cases  a  depression  more  or  less  marked.  The 
rostellum  may  or  may  not  be  contractile,  and  may  or  may  not  be  armed 
with  hooks. 

As  a  typical,  though  not  constant,  arrangement  of  the  reproductive 
organs,  those  of  the  species  Tcenia  saginata,  a  tapeworm  of  man,  are  here 
described.  Each  sexuall}'  mature  segment  (Fig.  90)  of  this  worm  has 
at  its  margin  a  protruding  genital  pore,  which,  from  segment  to  segment, 
is  irregularh'  upon  alternate  sides.  This  protuberance  contains  a 
cloaca-like  cavity  into  which  open  the  vas  deferens  and  vagina,  both  of 
which  extend  laterally  to  the  middle  of  the  segment.  Here  the  vas 
deferens  divides  into  a  number  of  seminal  ducts  which  are  distributed 
through  the  supporting  tissue  and  serve  to  carry  the  semen  from  the 
small  spherical  testes  which  are  located  almost  everywhere  in  the  seg- 
ment. As  it  approaches  the  lateral  cloacal  sac,  the  duct  becomes  con- 
voluted and  much  distended  with  the  accmnulated  seminal  fluid.  In  the 
vicinitA'  of  the  cloaca  it  develops  into  a  cirrus  (penis)  which  is  inclosed 
in  a  muscular  sheath. 

The  vagina  bends  downward  as  it  passes  toward  the  center  of  the 
segment  where  it  unites  with  the  paired  wing-like  ovaries  which  are 
rather  large  organs  consisting  of  branched  tubules.  In  the  posterior 
and  middle  portion  of  the  segment  is  a  single  organ,  hkewise  of  branched 


PLATYHELMINTHES 


171 


0    0     0  °  0  0   «t 
0    0   "o  •: 


tubular  structure, — the  viteUarium  or  yolk-gland,  the  secretion  from 
which  surrounds  the  eggs  in  the  cavity  of  the  shell-gland,  the  latter  a 
small  bod}^  consisting  of  compacth'  arranged  gland-cells  and  located 
just  above  the  vitelline  gland.  From  the  shell-gland  the  eggs  pass 
through  a  narrow  duct  into  the  uterus,  a  simple  tubular  organ  ascending 
directly  in  the  middle  of  the  segment  and  closed  at  its  distal  end.  The 
uterus    becomes    much     dis- 

l 


tended  from  the  accumulation 
of  eggs  and  develops  nu- 
merous lateral  branches  to 
which  the  other  sexual  organs 
gradually  give  place  until  lit- 
tle remains  of  them  but  ves- 
tiges of  the  vas  deferens  and 
vagina.  The  egg-engorged 
organ,  with  its  lateral  cecal 
pouches,  may  rupture,  or  the 
integument  of  the  segment, 
itself  may  give  wa}',  permit- 
ting the  eggs  to  escape  directly 
into  the  intestinal  contents. 
A§  a  rule  these  terminal  or 
''ripe"  segments  are  passed 
to  the  outside  of  the  body  of 
the  host  with  the  feces  where, 
by  their  disintegration,  the 
eggs  are  set  free. 

The   eggs   of   cestodes   are 
globular  or  more  or  less  oval 


11  ^/<j^ 

Fig.  ',)0. — SeKineut  of  TiPnia  saginata,  with 
sexual  organs  matured.  Ovaries  in  lower  portion 
to  right  and  left;  yolk  gland  in  extreme  lower 
portion;  shell  gland  between  yolk  gland  and  ova- 
ries; uterus,  tubular  organ  extending  upward; 
vagina,  extending  from  glands  to  genital  pore  at 
left  margin;  testis,  bodies  distributed  throughout 
segment;  vas  deferens,  convoluted  organ  extend- 
ing laterally  to  genital  pore.  Excretory  vessel 
united  by  transverse  commisures.  Lateral  longi- 
tudinal nerves  shown  by  heavy  lines. 


in  shape  and  are  provided  with  shells  of  variable  thickness  (Figs.  96 
and  110).  Beneath  the  shell  is  a  translucent  yolk  which  surrounds  an 
inner  covering  containing  the  onchosphere  (hexacanth)  or  six-hooked 
embryo  (Fig.  112,  a).  In  some  forms  the  eggs  as  found  in  the  feces 
often  have  the  outer  shell  absent. 

Life  History. — Species  of  Taeniidse  in  which  the  development  is 
known  undergo  a  complex  series  of  metamorphic  changes,  involving 
larval  and  sexually  mature  parasitism  in  hosts  of  differing  species. 
After  the  egg,  either  free  or  with  the  segment  entire,  has  been  ingested 
by  a  proper  larval  host,  the  shell  and  embryonic  envelope  are  digested 
away  by  the  gastric  juices,  and  the  onchosphere  is  freed  (Fig.  112,  a). 
At  this  stage  the  embrA'o  is  provided  with  three  pairs  of  booklets  by 
which  it  penetrates  the  intestinal  wall  and,  probably  by  blood  and 
l>auph  currents,  may  be  carried  to  certain  parts  of  the  body  specifically' 
essential  to  its  further  development.     Thus  passively  lodged,  it  loses 


172  PARASITES  OF  THE  DOMESTIC  ANIMALS 

its  booklets  and  commonly  becomes  smTOunded  by  a  capsule  formed  by 
proliferation  of  the  connective  tissue  of  the  host,  though  this  does  not 
occur  in  all  of  the  larval  forms. 

At  this  stage  the  larva,  which  is  now  a  mere  vesicle  containing  more 
or  less  fluid  and  as  yet  without  a  head,  is  referred  to  as  the  acephalocyst 
(bladder-cyst),  from  which  there  may,  in  certain  forms  (echinococcus), 
develop  multiple  daughter  cysts  (Fig.  117).  By  a  process  of  budding 
from  the  germinal  wall,  the  acephalocyst  now  develops  a  further  stage, — 
the  cephalocyst  (proscolex.  Fig.  112,  b  and  c),  containing  one  (cysticercus, 
Fig.  107)  or  more  (coenurus.  Fig.  114)  heads  which  conform  with  the 
scolex  of  the  adult  worm  except  that  the  larval  head  is  invaginated. 

If  the  larva  while  still  living  at  this  stage  is  conveyed  to  the  digestive 
canal  of  a  suitable  host  for  the  adult  worm,  the  head  is  evaginated  from 
the  vesicle  (Fig.  112,  c),  becomes  detached  from  it,  and,  passing  to  the 
intestine,  fixes  upon  the  mucosa  by  means  of  its  suckers,  to  which  attach- 
ment the  crown  of  hooks  contributes  if  this  is  present.  By  a  process  of 
budding,  the  scolex  now  proliferates  a  series  of  segments,  each  to  be- 
come bisexually  complete  (Fig.  90) . 

Sexual  maturity  of  the  segments  marks  the  stage  of  the  adult  worm 
which,  with  its  entire  series,  constitutes  the  chain,  or,  as  it  has  been 
called  by  most  writers,  the  strobila,  a  term  which,  with  that  of  proglottid 
for  segment,  is  discarded  in  this  work. 

Tabular  Review  of  Life  History  of  T^nia  Saginata 
Adult  Tapeworm  in  intestine  of  man 

I 
Egg. — Expelled  from  intestine. 

1 
Hexacanth. — Freed  from  egg  in  digestive  tract  when 

I  ingested  by  ox. 

Acephalocvst. — ^In  striated  muscle  of  ox. 

I 
Cephalocyst  (Cysticercus) .^Same. 

Scolex. — Attached  to  mucosa  of    intestine    of  man 

I  after  ingestion  of  cephalocyst. 

Adult  Tapeworm  in  intestine  of  man. 

Parasitism. — The  tapeworms  afford  an  example  of  extreme  para- 
sitism. So  far  as  known,  their  existence  is  wholly  dependent  upon 
alternate  cystic  and  adult  hosts,  their  development  exhibiting  no  free- 
living  stage.  So  advanced  is  their  degeneracy  that  there  is  little  of 
organization  remaining  excepting  the  procreative,  and  this  has  acquired 


PLATYHELMINTHES  173 

a  hyperdevelopment  adaptive  to  the  hazards  encountered  in  the  worm's 
life  history. 

The  classification  of  the  tapeworms  has  been  somewhat  more  artificial 
than  S3'stematic  in  that  it  has  not  sufficiently  taken  into  account  mode 
of  development,  a  factor  which  should  furnish  the  basis  for  their  true 
natural  affinities.  Their  larvae  may,  with  reference  to  method  of  develop- 
ment, be  placed  in  the  five  following  forms:  1.  Cijsticercus  (Fig.  107); 
2.  cotnurus  (Fig.  114);  3.  echinococcus  (Fig.  117);  4.  cysticercoid  (Fig. 
96);  5.  plerocercoid  (Fig.  112,-e).  The  first  three  are  found  in  organs 
or  serous  cavities  of  Herbivora  and  Omnivora,  occasionally  in  Carnivora; 
the  fourth  lives  mostlj'  in  invertebrates,  and  the  fifth  in  the  musculature 
of  fishes.  The  more  recent  tendency  in  cestode  nomenclature  is  to  con- 
fine the  generic  name  Taenia  to  those  tapeworms  which  have  a  cysticercus 
stage  in  their  life  history. 

The  cystic  forms  enumerated  above,  with  the  conditions  which  cer- 
tain of  them  produce  in  their  hosts,  are  taken  up  further  on  in  the  con- 
sideration of  the  cestode  larvae. 

The  accompanying  tabular  arrangement  of  the  principal  tapeworms 
considered  in  this  work,  with  their  adult  and  C3'stic  hosts,  is  inserted 
for  convenient  reference. 


CHAPTER  XV 

T.^NIASIS 

As  to  the  effect  of  tapeworms  upon  their  hosts,  it  may  be  said  in  gen- 
eral that  serious  disturbances  are  most  hkely  to  be  manifest  when  the 
worms  are  numerous,  in  which  case  the  morbid  effect  is  brought  about 
by  the  operation  of  several  factors.  There  may  be  a  reduction  or  com- 
plete occlusion  of  the  intestinal  lumen  with  the  usual  inflammatory  and 
toxic  disturbances  or  displacements  following  interruption  in  the  move- 
ment of  the  intestine's  contents.  While,  as  a  general  statement,  in- 
vasion of  the  bile  duct  by  tapeworms  may  be  said  to  be  rare,  the  fringed 
tapeworm  of  sheep  {Thysanosorna  actinioides)  frequently  enters  this 
organ  and  therefore  constitutes  a  more  serious  tseniasis  in  these  animals 
than  that  from  the  Moniezia  species.  Armed  tapeworms,  by  the  irrita- 
tion from  their  hooks,  will,  essentially,  set  up  an  inflammation  of  the 
mucosa  proportionate  to  their  number.  Further,  where  the  worms  are 
numerous,  their  appropriation  of  nourishment  contributes  to  the  mal- 
nutrition of  a  catarrhal  enteritis.  In  heavj^  infestations  the  toxins 
elaborated  by  the  worms  undoubtedly  play  a  considerable  part  in  the 
general  systemic  effect. 

The  cystic  forms  of  certain  tapeworms  have  an  important  bearing 
upon  the  sanitary  control  of  meat  food  products.  In  our  own  country 
this  is  especially  true  of  the  cysticerci  of  the  two  tapeworms  of  man, — 
Tcenia  saginata  and  T.  solium,  the  cysts  of  the  former  being  harbored 
in  beef,  those  of  the  latter  in  pork.  The  presence  of  these  cysts  in  the 
muscles  or  other  parts  of  the  bod}^  constitutes  the  disease  known  as 
measles,  to  which  affection  the  terms  ''measly  beef"  and  "measly  pork" 
have  reference.  While  observed  most  frequently  in  the  animals  men- 
tioned, measles  may  appear  in  sheep  {Cysticercus  tenuicollis,  C.  ovis), 
and  man  is  occasionally  auto-infected  by  larvae  (Cysticercus  cellulosce) 
of  Tcenia  solium  which  he  harbors. 

Cestodes  of  the  Horse 

Three  species  of  tapeworms  occur  in  the  Equidae.  In  all  the  cephalic 
armature  and  neck  are  absent,  and  all  have  a  genital  pore  on  the  same 
side  in  each  segment.    Nothing  is  known  of  their  larval  forms. 

1.  Anoplocephala  perfoliata  (Taenia  perfoliata).  Fig.  91.  Tseniidse 
(p.  170). — The  head  is  large,  rounded,  and  provided  with  well-developed 


.\dult 

Hosts 

Armature 

Anoplocephala  perfoliata 

Horse  and  ass 

Unarmed 

Anoplocephala  mamil- 
lana 

Horse  and  ass 

Unarmed 

Anoplocephala  plicata 

Horse  and  ass 

Unarmed 

Moniezia  expansa 

Cattle,  sheep  and 
goats 

Unarmed 

Moniezia  alba 

Cattle,  sheep  and 
goats 

Unarmed 

Moniezia  planissima 

Cattle,  sheep  and 
goats 

Unarmed 

Thysanosoma  actinioides 

Sheep 

Unarmed 

Dipylidium  caninum 

Dog,  cat,  man 

Armed 

Ta;nia  hydatigena 

Dog 

Arnied 

Taenia  pisiformis 

Dog 

Armed 

Multiceps  multiceps 

Dog 

Armed 

Multiceps  serialis     . 

Dog 

Armed 

Multiceps  gaigeri 

Dog 

Armed 

Echinococcus  granulosus 

Dog,  cat 

Armed 

Tania  taniajformis 

Cat 

Armed 

Cittotaenia  denticulata 

Rabbit 

Unarmed 

Choanotsenia  infundibu- 
lit'ormis 

Chicken 

Armed 

Hymenolepis  carioca 

Chicken 

Armed 

Davainea  tetragona 

Chicken 

Ai-med 

Davainea  cesticillus 

Chicken 

Armed 

Davainea  echinobothrida 

Chicken 

Ai-med 

Davainea  proglottina 

Chicken 

Armed 

Taenia  saginata 

Man 

Unarmed 

Taenia  solium 

Man 

Armed 

Ciphyllobothrium  latum 

Dog,  cat,  man 

Unarmed 

Hosts 

Parts  Infested  by  Larva 

Flea,  louse 

Body-cavity 

Ruminants  and  hogs 

Peritoneum 

Rabbit 

^Mesentery  and  omentum 

Herbivora 

Central  nervous  system 

Rabbit  and  other  ro- 
dents 

Connective  tissue 

Ruminants 

Central  nervous  system  and 
connective  tissue 

Ruminants  and  hog 

Liver  and  lungs 

Rat  and  mouse 

Liver 

House  fly 

Snail 

Ox 

Connective  tissue  of  muscles 

Hog  and  other  animals 

Connective  tissue  of  muscles 

Fish 

Muscles 

T.^NIASIS 


175 


suckers;  it  is  prolonged  behind  by  rounded  flaps  on  the  upper  and  lower 
side.  The  segments  are  very  short,  but  wide,  the  width  increasing 
toward  the  middle  of  the  length  of  the  body. 

Length,  2.5-3  cm.  (1  inch);  width,  3-15  mm.  (1/8-5/8  of  an  inch). 

The  eggs,  by  mutual  pressure,  are  polygonal.  The  shell,  as  in  other 
Anoplocephalinae,  is  prolonged  by  a  pyriform  point.  They  are  70-80 
microns  in  length. 

It  lives  in  the  small  intestine  and  ceemn,  more  rarely  in  the  colon. 

2.  Anoplocephala  mamillana  (TaBnia  mamillana).  Fig.  91. 
Tsniidse  (p.  170). — The  head  is  small,  somewhat  angular,  and  has  a 
central  lineal  depression  from  before  to 
behind.  It  is  provided  with  oval  suckers 
located  upon  the  side.  The  segments  are 
nuich  wider  than  long,  progressively  in- 
creasing in  width  from  the  head.  Their 
length  increases  toward  the  posterior  ex- 
tremity, the  last  segments  being  about 
half  as  long  as  broad. 

Length,  1-5  cm.  (3/8-2  inches);  width, 
4-6  mm.  (i<4  of  an  inch). 

The  eggs  are  elongated  and  about  88 
microns  in  length. 

It  infests  the  small  intestine. 

3.  Anoplocephala  plicata  (Taenia 
plicata).  Fig.  91.  Ta^niidse  (p.  170).— 
The  head  is  rather  large,  broader  than 
long,  slightly  concaved  in  the  center. 
The  four  suckers  are  strong  and  are  di- 
rected forward.  The  segments  progres- 
sively increase  in  breadth  and  length  to 
the  posterior  extremity. 

Length,  8-12  cm.  (3  1/8-4  ^  inches); 
width,  8-20  mm.  (5/16-^^  of  an  inch). 

The  eggs  are  polygonal  or  round  and  50-60  microns  in  length. 

It  lives  in  the  small  intestine  and  has  been  found  in  the  stomach. 

Occurrence. — Horses  rarel}'  harbor  tapeworms.  They  are  said  to 
be  most  often  found  in  the  horses  of  Russia  and  to  some  extent  in 
Germany  and  other  European  countries.  The  most  common  species  is 
Anoplocephala  perfoliata,  while  of  the  other  two  mentioned,  Anoplo- 
cephala plicata  is  the  luore  rare. 

Symptoms. — The  presence  of  tapeworms  in  the  intestines  of  the 
horse  is  seldom  accompanied  by  perceivable  symptoms.  Those  general 
to  intestinal  helminthiasis,  as  chronic  digestive  disturbances,  with  per- 
haps anaemia  and  general  unthrift,  may  accompany  the  infestation, 


Fig.  91. — Tapeworms  of  the  horse. 
Left  to  right:  Anoplocephala  mamil- 
lana, A.  perfoliata,  A.  plicata,  nat- 
ural size. 


176 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


though  it  can  only  be  assumed  that  these  symptoms  are  caused  by  tape- 
worms, even  though  the  presence  of  the  worms  is  made  certain  by  the 
voiding  of  the  segments. 


Cestodes  of  Cattle,  Sheep,  and  Goats 

Cattle  harbor  three  species  of  tapeworms.  In  all  the  heads  are  un- 
armed.   Their  larval  forms  are  unknown. 

The  three  species  of  tapeworms  of  cattle  also  occur  in  sheep  and^ 
goats. 

1.  Monieziaexpansa  (Taenia  expansa).  Fig.  92.  Tseniidae  (p.  170). 
The  head  is  small,  generally  pear-shaped.  The 
suckers  are  slightly  salient  and  slit-like.  The  an- 
terior part  of  the  chain  is  filiform.  The  first  seg- 
ments are  very  short,  those  which  follow  becoming 
longer,  but  always  much  broader  than  long.     The 

Is      =      ^    broadest  segments  may  reach  a  breadth  of  2  cm. 
=       =    (3<£  of  an  inch).     The  genital   pores   are  double 
M     =       ^    and   located  on  the    lateral  margins  of  the  seg- 
ments. 

The  length  varies  considerably;  it  msiy  be  15-30 
feet  or  more. 

The  eggs  are  globular  or  polygonal  and  are  50-90 
microns  in  diameter. 

2.  Monieziaalba  (Taenia  alba).  Tseniidse  (p.  170). 
— The  head  is  larger  than  that  of  the  preceding 
species  and  is  provided   with  large  oval  suckers. 
The  neck  is  short  and  the  segments  are  longer  and 
narrower  than  in  M.  expansa;  some  may  be  slightly 
Moniezia   longer  than  broad.    The   width   of   the   broadest 
segments  is  about  1  cm.  (3/8  of  an  inch).     There 
are  two  genital  pores  in  each  segment. 
Its  maximum  length  is  about  eight  feet. 
The  eggs  are  cuboidal  and  48-58  microns  in  breadth. 
3.  Moniezia  planissima.  '  Tseniidse  (p.  170). — The  head  is  nearly 
square  and  has  slightly  elongated  suckers.     The  segments  are  much 
broader  than  long,  the  ripe  ones  having  a  width  of  12-26  mm.  (3^-1 
inch).    These  segments  are  very  thin  and  semitransparent.    Each  seg- 
ment has  two  genital  pores. 
Length,  3-6  feet. 

The  eggs  are  about  63  microns  in  diameter. 

Thysanosoma  actinioides  (Taenia  fimbriata).  Tseniidse  (p  170.). — 
This  is  a  species  occurring  in  sheep,  but  has  not  been  reported  in  other 
domesticated  Herbivora.    The  head  is  without  hooks  or  rostellum.    The 


Fig.  92. 
expansa,  portions  of 
adult,  reduced  (after 
Railliet). 


T.EXIASIS  177 

segments  are  broader  than  long,  having  the  uterus  transverse  and  the 
genital  pores  double  or  irregularly  alternate.  The  segments  have  long 
fringes  on  their  posterior  borders  (Fig.  93). 

Length,  six  inches  or  more. 

Its  larval  form  is  unknown. 

Occurrence  and  Symptoms. — All  of  these  worms  live  in  the  small 
intestine.  As  nothing  is  yet  known  of  their  cystic  forms,  the  mode  of 
infection  remains  undetermined.  Cattle  are  rarely  disturbed  in  health 
by  the  presence  of  tapeworms.  In  exceptional  cases  there  may  be 
malnutrition  and  digestive  disturbances  accompanied  by  bloating. 
Again,  it  is  difficult  to  with  certainty  assign  these  nonspecific  condi- 
tions to  the  presence  of  tapeworms.  As  in  all  intestinal  helminthiases, 
there  is  to  be  borne  in  mind  the  possibility  of  the  worms  passing  to 
unusual  locations,  as  the  bile  ducts,  and  of 
interference  with  the  movement  of  the  in- 
testinal contents  by  massed  worms. 

Of  the  domesticated  herbivorous  animals, 
probably  sheep  most  frequently  harbor  tai^e- 
worms.  A  species  often  found  in  those  of 
the  United  States  is  Thijsanosoma  aclinioidcs 
Avhich,  as  is  true  of  other  species  infesting 
sheep,  is  most  prevalent  among  the  flocks  of  Fig.  93.— Thysanosoma  ac- 
the  Western  States.  The  worms  may  be  tinioides,  anterior  segments,— 
found  at  an}'  time  of  the  year,  though  more  ^^  ^'^^^ 
often  during  the  season  of  grazing,  a  fact  pointing  to  the  probability 
that  the  encysted  larvae  are  taken  up  with  the  grass.  Thysanosoma 
actinioides,  when  brought  to  certain  parts  of  the  Eastern  United  States, 
does  not  multiply.  It  may  be  assumed  that  this  is  attributable  to 
absence  of  the  proper  intermediate  host,  whatever  that  may  be.  In 
parts  of  the  west  it  constitutes  a  form  of  taeniasis  much  more  severe  than 
that  from  ]\Ioniezia.  This  is  due  mainly  to  their  invasion  of  the  bile 
duct,  a  habit  which  is  exceptional  with  other  tapeworms,  but  with  the 
fringed  tapeworm  it  is  the  rule  rather  than  the  exception. 

Lambs  born  in  the  winter  and  turned  upon  grass  during  the  rains 
and  moisture  of  spring  are  the  more  likely  to  suffer  from  tapeworm 
invasion.  In  such  cases,  or  in  hea\y  infestation,  anaemia  is  indicated 
by  paleness  of  the  \asible  mucosae,  and  this  may  be  accompanied  by 
loss  of  vivacity  and  more  or  less  emaciation  with  arrest  in  development. 
Straining  and  ineffectual  efforts  at  defecation,  with  prolonged  elevation 
of  the  tail,  are  noticed,  the  feces  later  becoming  unformed  or  even  fluid 
and  containing  the  segments. 

Death  ma}'  ensue  in  advanced  emaciation  and  weakness,  or  before 
reaching  this  stage  if  the  intestine  becomes  obstiiicted  by  the  worms 
in  mass  or  there  are  other  resulting  complications.     Such  a  course  is 


178  PARASITES  OF  THE  DOMESTIC  ANIMALS 

rare  in  aged  sheep.    Where  fatahties  occur,  they  are  usually  among  the 
grazing  lambs. 

Cestodes  of  the  Dog 

Of  the  tapeworms  of  the  dog,  nine  are  considered  here,  among  which 
there  is  a  wide  variation  as  to  frequency  and  importance.  The  first 
eight  of  the  species  to  be  mentioned  belong  with  the  family  Taeniidae; 
the  ninth  is  referred  to  under  the  Diphyllobothriidse.  In  all  but  the 
last  the  head  is  provided  with  the  crown  of  hooks,  and  in  all  the  life 
history  is  known. 

1.  Dipylidium  caninum  (Taenia  cucumerina) .  Fig.  94.  Taeniidse 
(p.  170). — The  head  is  small  and  has  a  protractile  rostellum  surrounded 
by  the  four  suckers  (Fig.  95).  There  are  three  to  four  rows  of  small 
thorn-like  hooks.  The  neck  is  slender,  succeeded  at  first  by  narrow 
trapezoidal  segments.  The  nature  segments  are  longer  than  wide  and 
shaped  somewhat  like  a  cucumber  seed.  They  have  a  genital  pore  on 
each  lateral  margin. 

Length,  15-40  cm.  (6-16  inches). 

Eggs  globular,  43-50  microns  in  diameter  and  grouped  in  small  cap- 
sules (Fig.  96). 

The  larva  of  this  worm  is  a  cysticercoid  {Cryptocystis  trichodedes) 
found  in  the  body-cavity  of  the  biting  louse  of  the  dog, — Trichodedes 
latus  (Fig.  96).  Lice  are  not  sufficiently  prevalent  upon  dogs,  however, 
to  account  for  the  frequent  occurrence  of  this  worm;  in  fact,  later  in- 
vestigations have  determined  that  the  dog  flea,  Ctenocephalus  cams, 
and  the  human  flea,  Pidex  irritans,  harbor  its  larva,  and  it  is  probable 
that  the  flea  is  its  more  common  host. 

2.  Dipylidium  sexcoronatum.  Tseniidse  (p.  170). — Hall  and  Wigdor 
(Journal  of  the  American  Veterinary  Medical  Association,  June,  1918) 
refer  to  this  tapeworm  as  follows:  "Dipylidium  sexcoronatum  has  been 
reported  from  dogs  in  the  United  States  at  Bethesda,  Md.,  and  Detroit, 
Mich.,  by  Hall  (1917).  We  find  it  fairly  often  here  at  Detroit  and  our 
impression  is  that  it  is  as  common  here  as  D.  caninum.  The  strobila  is 
much  narrower  than  D.  caninum.  Some  of  the  specimens  with  a  narrow 
strobila  appear  to  have  only  five  rows  of  hooks  and  should  be  studied 
with  a  view  to  determining  whether  D.  sexcoronatum  has  sometimes  five 
rows  of  hooks,  as  well  as  six  rows,  or  whether  this  material  belongs  to  a 
new  species." 

3.  Taenia  hydatigena  (T.  marginata).  Fig.  97.  Taeniidse  (p.  170). — 
The  head  is  small,  but  little  broader  than  the  neck.  The  hooks  are 
large,  170-220  microns  long,  and  number  30-34.  The  mature  segments 
are  wider  than  long,  the  distal  segments  elongated.  The  gravid  seg- 
ments have  a  median  longitudinal  groove  terminating  in  a  notch  pos- 


TiENIASIS  179 

teriorly.  The  number  of  segments  is  about  400.  The  gravid  uterus  has 
5-10  branches  on  each  side. 

Length,  1.5-2  meters  (57-76  inches). 

Eggs  nearly  spherical  and  31-36  microns  in  diameter. 

The  larva  is  a  cysticercus  (Csyticercus  tenuicollis)  found  in  the  per- 
itoneum and,  more  rarely,  in  the  pleura  of  loiminants  and  hogs.  It  has 
also  been  reported  from  rotlonts  and  monkeys. 

4.  Taenia  pisiformis  (T.  serrata).  Fig.  98.  Tseniidse  (p.  170). — 
The  head  is  small,  but  little  broader  than  the  neck.  The  hooks  are 
large,  225-294  microns  long  and  34-38  in  number.  The  segments  are 
at  first  narrow  and  much  shorter  than  broad;  those  mature  are  approx- 
imatel}'  square.  The  distal  segments  are  elongated  (10-15  mm.  by 
4-6  mm.).  The  posterior  margins  of  the  segments  project  laterally, 
giving  to  the  lateral  margins  of  the  chain  a  serrated  appearance.  The 
genital  pores  are  prominent,  and  the  utenis  in  gravid  segments  has  8-14 
lateral  branches  on  each  side. 

Length,  0.5-2  meters  (19-76  inches). 

Eggs  oval,  36-40  microns  long,  31-36  microns  wide. 

The  larva  is  a  cysticercus  (Cysticercus  pisiformis)  which  develops  in 
the  mesentery  and  omentum  of  rabbits,  and  has  been  found  in  the  mouse 
and  beaver. 

5.  Multiceps  multiceps  (Taenia  coenurus).  Fig.  113.  Tseniidse 
(p.  170).— The  head  is  small  and  bears  22-30  hooks.  Larger  hooks  have 
a  handle  equal  in  length  to  that  of  the  blade  and  wavy  in  outline.  The 
segments  of  the  middle  portion  of  the  chain  arc  approximately  square. 
The  distal  segments  are  elongated  (8-12  mm.  long  by  3-4  mm.  wide). 
The  ripe  segments  are  broader  at  their  middle,  narrowing  toward  their 
ends  which  gives  them  somewhat  the  appearance  of  a  cucumber  seed. 
The  genital  organs  are  well  developed,  15-20  cm.  (6-8  inches)  from  the 
head,  or  toward  the  125th  segment.  The  genital  pores  are  irregularly 
alternate.    The  uterus  has  16-25  lateral  branches  on  each  side. 

Length,  40-60  cm.  (16-23^  inches). 

Eggs  nearly  spherical  and  31-36  microns  in  diameter. 

The  larva  is  a  coenurus  (Multiceps  multiceps;  Coenurus  cerebralis) 
which  develops  in  the  cerebral  cavity  and,  more  rarely,  in  the  spinal 
canal  of  herbivora,  usually  sheep  (Figs.  114  and  116). 

6.  Multiceps  serialis  (Taenia  serialis).— Tseniidse  (p.  170).  The 
head  is  a  little  wider  than  the  neck  and  bears  26-32  hooks.  The  small 
hooks  have  a  short  blunt  handle;  the  larger  hooks  a  wavy  handle  as 
long  or  a  little  longer  than  the  blade.  The  segments  are  similar  to  those 
of  M.  multiceps,  the  form  of  the  uterus  in  gravid  segments  also  being  the 
same. 

Length,  44-74  cm.  (17-293^  inches). 

Eggs  oval,  34  microns  long,  27  microns  wide. 


Fig.  96. — Egg  packet  of  Dipylidium 
caninum  (left);  Cysticercoid  (right). 


Fig.  95. — Head  of 
Dipylidium  caninum, 
with  I'ostellum  pro- 
jected. 


Fig.  94.— Dipyli- 
dium caninum,  por- 
tions of  adult,— ^ 
natural  size. 


Fig.   9S.  —  Taenia    pisiformis, 
portions  of  adult, — natural  size. 


Fig.  97.  —  Tsenia  hydati- 
gena,  portions  of  adult. — nat- 
ural size. 


T.ENIASIS  181 

The  larva  is  a  coeniirus  (Multiceps  serialis;  Ccenurus  serialis)  found 
in  the  connective  tissue  of  rabbits  and  other  rodents. 

7.  Multiceps  gaigeri.  Taeniidae  (p.  170). — This  is  a  species  found 
in  India  and  Ceylon,  and  described  b}'  Hall  (Journal  of  the  American 
Veterinarj'^  Medical  Association,  November,  1916),  the  larva  of  which 
develops  m  the  central  nervous  system  and  also  in  the  connective  tissues 
and  serous  surfaces  of  ruminants.  Thus  in  its  cystic  host  this  species 
combines  the  location  of  M.  multiceps  and  M.  serialis,  the  larva,  as  in 
that  of  the  latter,  forming  an  adventitious  capsule. 

The  material  for  examination  (Bureau  of  minimal  Industrj^,  Hel- 
minthological  Collection)  consisted  of  specimens  of  tapeworms  from 
the  dog  and  the  ccenurus  from  the  goat.  From  his  stud}'  of  these,  Hall 
(1916)  regards  this  species  as  more  closeh^  related  to  the  gid  tapeworm, 
M.  multiceps,  than  to  M.  serialis. 

8.  Echinococcus  granulosus  (Taenia  echinococcus).  Fig.  99. 
Taeniidae  (p.  170). — The  chain  is  but  4-6  nun.  (3/16-1/4  of  an  inch)  in 
length,  and  is  composed  of  a  head  and  three  segments.  The  head  is 
provided  with  28-50  small  hooks  arranged  in  two  rows.  The  first  and 
second  segments  from  the  scolex  are  incompletely  developed,  but  one 
segment  at  a  time  becoming  gravid, — the  third,  when  its  length  almost 
reaches  that  of  the  rest  of  the  worm. 

Eggs  oval,  32-36  microns  long,  25-26  microns  broad.   . 

The  larva  is  an  echinococcus  {Echinococcus  granulosus;  E.  polymor- 
phus)  found  in  the  internal  organs,  usually  the  liver  and  lungs,  of  rumi- 
nants and  hogs,  and  also  in  man  (Fig.  117). 

Occurrence. — It  follows  from  their  habits  that  dogs  should  more 
frequently  harbor  intestinal  parasites  than  other  domestic  anunals. 
Probably  over  fifty  per  cent,  are  infested  with  varied  species,  frequently 
in  considerable  number.  Of  these,  tapeworms  predominate,  several 
species  of  which  often  inhabit  the  intestine  of  a  single  individual. 

The  intermediate  hosts  of  Dipylidium  caninum — fleas  and  lice,  the 
former  ubiquitous  in  relation  to  canine  existence, — would  account  for 
the  greater  frequenc.y  of  this  tapeworm  than  any  other  in  dogs.  Dogs 
which  have  access  to  butchers'  offal  are,  in  addition  to  this  species, 
readily  infected  with  Echinococcus  gramdosus,  Tcenia  hydatigena,  and 
Multiceps  multiceps,  the  cystic  forms  of  which  are  harbored  in  organs 
of  the  principal  meat-food  animals,  sheep,  hogs,  and  cattle.  Hunting 
dogs  and  those  which  roam  afield  are  the  most  exposed  to  invasion  with 
TcBnia  pisiformis  and  Multiceps  serialis,  these  having  their  larval  devel- 
opment in  rabbits.  In  an}^  case,  young  dogs  are  more  susceptible  to 
intestinal  helminthiasis  than  those  which  are  older. 

Symptoms, — Notwithstanding  their  frequent  presence  in  large  num- 
bers, tapeworms  seem,  as  a  rule,  to  have  little  deleterious  influence 
upon  the  health  of  dogs.     As  is  tme  of  intestinal  worms  in  general, 


182  PARASITES  OF  THE  DOMESTIC  ANIMALS 

their  accumulation  may  bring  about  obstruction  with  attendant  dis- 
placement and  degenerative  changes  in  the  intestinal  walls;  and,  again, 
there  ma}''  be  a  serious  and  even  fatal  result  from  their  unusual  location. 
Such  consequences  of  taeniasis  are,  however,  exceptional  in  dogs.  In 
general,  the  s\miptoms  are  those  of  chronic  gastro-intestinal  catarrh. 
The  capricious  appetite  varies  between  extreme  voraciousness  and  com- 
plete anorexia.  Regardless  of  the  amount  of  food  consumed,  there  is  a 
noticeable  emaciation  which  may  become  well  marked,  young  dogs 
especially  becoming  pot-bellied  and  stunted  in  growth.  More  char- 
acteristic is  restlessness,  straining,  and  itching  about  the  anus,  the  latter 
manifested  by  agitation  of  the  tail  and  a  peculiar  squatting  and  dragging 
of  the  hind  parts,  sometimes  referred  to  in  the  expressive,  but  highly 
untechnical  term,  ''rough-locking." 

With  increasing  uneasmess,  the  development  of  intestinal  pains, 
howling,  and  an  inclination  to  bite,  which  is  perhaps  conjoined  with  a 
dull  or  wild  expression,  there  are  presented  symptoms  somewhat  similar 
to  those  of  rabies.  In  such  cases  convulsions  may  set  in  and  the  animal 
may  die  during  an  attack,  or  it  may  gradually  succumb  after  sinking 
into  a  cataleptic  condition. 

Pathogenesis. — Necropsies  upon  dogs  which  have  suffered  from 
taeniasis  generally  show  the  worms  lodged  in  the  small  intestine  only. 
Probably  as  a  result  of  post-mortem  wandering,  they  may  also  be  found 
in  small  numbers  in  the  large  mtestine  or  stomach.  The  inflammation  of 
the  mucosa  is  especially  extensive  and  of  aggravated  character  in  in- 
festation with  Echinococcus.  This  is  a  tapeworm  of  the  dog  which, 
though  relatively  very  small,  sets  up  the  greatest  irritation  bj'-  reason 
of  the  vast  number  of  individuals  present,  w^hich,  firmly  implanted  by 
their  hooks,  may  completely  cover  the  intestinal  lining  over  large  areas. 
Where  obstruction  occurs  in  taeniasis,  it  is  generally  brought  about  by 
the  presence  of  the  larger  tapeworms  massed  in  coils.  Dipylidium 
caninwn,  though  smaller  than  some  other  species  inhabiting  the  dog,  is 
most  likely  to  be  found  the  offending  agent  in  such  conditions  because 
of  its  prevalence  and  the  presence  of  numerous  individuals  in  the 
same  host.  The  projecting  rostellum  of  this  species,  sinking  deep 
into  the  mucosa,  is  also  a  factor  increasing  its  capabilities  for  dam- 
age. Tcenia  hydatigena  and  T.  pisiformis  are  much  larger,  but  less 
common,  while  Midticeps  multiceps  and  M.  serialis  have  thus  far 
been  found  more  commonly  in  European  countries  than  in  the 
United  States. 

Contributing  to  the  systemic  effects  of  tapeworm  invasion,  there  is, 
as  in  other  helminthiases,  the  operation  of  toxins  elaborated  by  the 
worms."  In  cases  of  heavy  infestation  this  factor  must  be  a  considerable 
one,  especiallj'  when  combined  with  that  of  poisons  derived  from  the 
dead  and  decomposing  bodies  of  the  parasites. 


TiENIASIS  183 

Diagnosis. — The  presence  of  tapeworms  may  in  most  cases  be  recog- 
nized b}"  the  passing  of  segments,  or  fragments  of  the  chain,  with  the 
feces;  occasionally  these  may  also  be  expelled  with  vomited  matter. 
Often  the  fragments  may  be  arrested  near  or  partly  protrude  from  the 
anus,  causing  a  pruritus  in  this  region  which  the  animal  endeavors  to 
relieve  by  rubbing  the  parts  upon  the  ground. 

Diagnosis  may  be  assisted  in  doubtful  cases  by  the  administration 
of  a  laxative,  in  the  operation  of  which  detached  portions  of  the  chain 
will  be  expelled  if  present.  Echinococcus,  however,  on  account  of  its 
small  size,  is  likely  to  escape  observation  in  the  ordinary  means  of 
examining  fecal  matter. 

Dog  Tapeworms  in  Relation  to  Human  Infection. — Two  species  of 
tapeworms  harbored  by  dogs — Echinoccocus  granulosus  and  Dipylidium 
caninum — are  especially  of  medical  interest  in  that  they  ma}'  also 
infect  man.  The  first  mentioned  produces  in  its  larval  development  a 
condition  known  as  hydatid  disease,  or  echinococcosis,  in  man  as  well 
as  in  numerous  lower  animals. 

The  larval  or,  as  it  is  called,  the  hydatid  form  of  this  tapeworm  occurs 
usually  in  the  liver,  lungs  and  kidneys  of  these  animals,  and  may  pro- 
duce from  the  original  cyst  numerous  daughter  cysts,  the  growth  going 
on  indefinitely  and  evolving  bladders  as  large  or  even  much  larger  than 
an  orange  (Fig.  117).  Due  to  its  pressure,  necrotic  degeneration  of 
tissue,  and  also  to  secondary  infection  by  bacteria,  this  growth  gives 
rise  to  serious  disturbances  in  the  organ  in  which  it  is  lodged.  In  man 
the  condition  is  often  fatal,  less  so  in  the  lower  animals,  probably  owing 
to  the  fact  that  their  term  of  life  is  shorter,  or  they  are  likely  to  be 
slaughtered  before  sufficient  time  has  elapsed  for  the  full  development 
of  the  slow-growing  hydatid. 

A  more  detailed  reference  to  the  echinococcus  c.vst  is  given  further 
on  in  the  special  consideration  of  the  cestode  larvse  (p.  210). 

The  connnon  tapeworm  of  the  dog,  Dipylidium  caninum,  may  find 
adult  hostage  in  the  human  intestine.  According  to  Hall  (Bull.  260, 
U.  S.  Dept.  of  Agriculture,  1915),  seventy-six  cases  of  this  tapeworm 
in  man,  mostly  children,  have  been  reported,  a  number  of  these  from 
the  United  States.  It  has  been  found  in  an  adult  thirty-eight  years  old, 
and  it  is  stated  that  as  many  as  two  hundred  and  fifty-eight  of  these 
worms  have  been  found  in  a  single  person. 

Considering  the  privileges  which  are  allowed  dogs,  it  is  quite  apparent 
that  a  flea  or  louse  containuig  the  Cryptocystis  might  pass  from  the  dog 
to  the  human  mouth  by  the  dog  licking  the  face,  or  through  the  inter- 
mediation of  food,  especially  sticky  candy  to  which  the  insect  readily 
adheres.  Children  give  little  attention  to  incidental  contamination 
of  their  food,  which  is  frequently  partaken  of  in  intimate  proximity  to 
their  canine  companions,  the  dog  often  sharing  in  the  feast — perhaps 


184  PARASITES  OF  THE  DOMESTIC  ANIMALS 

from  the  same  plate.  It  follows  that  human  mfection  with  this  tape- 
worm occurs  more  often  among  children  than  among  adults. 

As  in  tseniasis  of  other  animals,  the  presence  of  a  few  of  these  worms  in 
man  is  not  likely  to  occasion  serious  disturbance,  though  to  the  human 
conception,  the  presence  of  a  tapeworm  in  the  intestine  is  anything 
but  a  pleasant  thing  to  contemplate.  Where  they  are  numerous,  the 
irritation,  possible  obstruction,  and  other  secondary  compHcations  which 
may  arise,  make  it,  as  in  lower  animals,  a  more  serious  condition. 

Prevention  calls  for  restraint  in  the  liberties  of  dogs,  especially  about 
children.  Children  should  not  be  permitted  to  handle  vagrant  and 
neglected  dogs.  Those  kept  about  the  premises  as  pets  should  be  ob- 
served for  indications  of  the  presence  of  tapeworms,  and  their  bodies 
should  be  kept  free  from  fleas  and  lice. 

Cestodes  of  the  Cat 

Of  the  tapeworms  harbored  by  cats,  onl}^  the  species  Tcenia  tcenice- 
formis  is  of  importance  as  affecting  their  health.  Others  which  have 
been  found  are:  Dipylidimn  caninum,  Echinococcus  granulosus,  and 
Diphyllobothrium  latum,  the  first  two  described  under 
the  Tseniidse  of  the  dog.  These  latter  forms  do  not 
appear  to  cause  disturbance  to  the  animal. 

Taenia  taeniseformis  (T.  crassicollis).  Tseniidse 
(p.  170).— The  head  (Fig.  100)  is  rounded,  has  four 
prominent  suckers  and  a  strong  rostellum  provided 
with  26-52  hooks.  The  neck  is  as  wide  as,  or  wider 
than,  the  head,  and  there  is  no  intermediate  constric- 
FiG.  100.— Head  of  tion.  The  segments  follow  immediately  from  the  head, 
Taenia   taeniaeformis,  increasing  in  size  to  a  length  of  8-10  mm.  (5/16-3/8 

Length,  15-60  cm.  (6-23i^  inches). 

Eggs  globular,  31-37  microns  in  diameter. 

The  larva  is  a  cysticercus  (Cysticercus  fasciolaris)  inhabiting  the 
liver  of  rats  and  mice. 

Occurrence  and  Symptoms. — This  tapeworm  is  not  uncommon 
in  the  cat,  often  infesting  the  small  intestine  in  large  numbers  and 
seriously  affecting  the  animal. 

There  is  in  the  beginning  a  diminution  of  appetite  which  gradually 
passes  to  refusal  to  take  any  food  whatever.  Diarrhea,  at  first  slight,, 
later  severe,  is  succeeded  by  constipation;  there  is  salivation,  and  in 
some  cases  vision  and  hearing  are  seriously  affected.  Colic  is  a  frequent 
accompaniment  during  the  attacks  of  which  the  animal  may  rush  about 
in  a  frantic  manner,  apparently  heedless  of  or  unable  to  see  objects  with 
which  it  may  come  in  contact. 


T.ENIASIS  185 

Finally,  as  a  manifestation  of  the  nervous  disturbance,  there  are 
convulsions;  there  is  much  prostation  and  emaciation,  and  the  animal 
dies,  usually  during  or  shortly  after  an  epileptiform  attack. 

Cestodes  of  Rabbits 

Tapeworm  infection  is  said  to  frequently  appear  enzooticall}'  among 
the  wild  hares  of  foreign  countries.  In  domestic  rabbits  such  infection 
is  rare.  The  species  here  described  is  occasionally  found.  It  is  unarmed, 
and  its  life  history  is  unknown. 

Cittotaenia  denticulata  (Moniezia  denticulata).  Tseniidse  (p.  170). — 
The  head  is  small,  with  fiat  suckers.  The  neck  is  as  broad  as  the  head. 
The  larger  segments  may  be  10  mm.  (3/8  of  an  inch)  in  width,  always 
wider  than  long.  The  genital  pores  are  on  the  posterior  fourth  of  the 
border  of  the  segment. 

It  may  reach  a  length  of  8  cm.  (3  inches). 

There  is  little  clinical  experience  with  taeniasis  of  rabbits.  In  general, 
what  has  been  said  as  to  such  infection  in  other  animals  will  apply  as 
well  to  them.  Diagnosis  can  be  made  by  finding  the  segments  in  the 
feces,  or  by  destroying  and  examining  one  or  two  suspected  animals. 

Family  II.  Diphyllobothriid.e 

The  best  known  representative  of  this  family  is  DiphyUobothrium 
latum  (Dibothriocephalus  latus,  Bothriocephalus  latus).  The  head  is 
oblong  or  lanceolate,  unarmed,  and  has  two  deep  slit-like  depressions, 
one  dorsal,  the  other  ventral,  which  serve  as  suckers  (Fig.  109).  The 
neck  is  not  well  demarcated  from  the  first  segments  which  are  scarcely 
visible.  The  segments  gradually  increase  in  length  and  breadth;  the 
largest  are  4-5  mm.  long  and  may  be  2  cm.  wide  (3/16  by  3/4  of  an 
inch).  The  gravid  segments  become  much  narrower  as  their  genital 
organs  atrophy  and  the  eggs  are  discharged,  these  being  expelled  in 
greater  part  before  the  separation  of  the  segments  from  the  chain.  In 
sexually  mature  segments  the  rosette-shaped  uterus  may  be  seen  in  the 
middle  line.  The  genital  pores  are  special  orifices  for  ovulation,  located 
in  the  middle  of  the  ventral  surface  of  the  segments  (Fig.  101). 

The  length  of  the  entire  worm  may  be  2-7  meters  (6-22  feet).  It 
may  reach  a  length  of  20  meters  (Neumann).  The  segments  may 
number  3,000  or  more. 

The  eggs  are  oval,  operculated,  and  68-70  microns  long.  In  the 
presence  of  water  a  ciliated  embryo  escapes  from  the  egg  by  the  lifting 
of  the  operculum  and  swims  about  until  it  enters  the  body  of  a  iresh- 
water  fish,  said  to  be  especially  the  pike.  In  the  muscles  of  this  host  it 
develops  into   the  worm-Hke  plerocercoid   (Fig.   112,   e).      After  the 


186 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


definitive  host  has  eaten  fish  containing  the  hving  kirvse,  the  tapeworms 
develop  rapidly,  becoming  mature  in  about  four  weeks. 

Occurrence. — This  species  is  sometimes  called  the  broad  Russian 


IS^'f i  lUBtti 


Fig.  101. — Sections  of  Diphyllobothrium  latum, — natural  size  (after  Boas,  by  Kirkaldy 
and  Pollard,  from  Leuckart). 

tapeworm.  It  infests  man  and  fish-eating  dogs  in  Russia,  Switzerland, 
Japan,  Finland,  Sweden,  and  other  foreign  countries.  It  is  extremely 
rare  in  the  United  States,  and  is  of  little  medical  or  economic  importance 
here. 

Teeatment  of  T^niasis 

Treatment  of  Taeniasis  of  the  Dog. — Therapeutic  measures  for  the 
expulsion  of  tapeworms  have  two  consecutive  objects  in  view;  first,  the 
bringing  about  of  a  torpid  condition  or  weakening  of  the  worm;  second, 
the  expulsion  of  the  entire  worm  from  the  host.  The  first  is  attained  in 
part  by  depriving  the  parasite  of  its  nourishment,  and  by  the  adminis- 
tration of  a  vermifuge  which  should  sufficiently  further  weaken  it  to 
cause  its  detachment  from  the  mucosa;  the  second  by  a  purgative  which 
will  expel  the  detached  worm  with  the  evacuations. 

As  preparatory  to  the  action  of  the  vermifuge,  all  food  should  be  kept 
from  the  animal  for  at  least  twenty-four  hours  immediately  preceding 
its  administration;  at  the  same  time  the  cleaning  out  process  will  be 
considerably  aided  if  a  mild  laxative  is  given.  Some  advocate  a  milk 
diet  for  several  days,  but  in  any  case  the  fasting  should  be  absolute  for 
a  period  of  one  day. 

Of  the  vermifuge  agents,  those  which  have  been  found  most  reliable 
as  taeniafuges  are:  (1)  male  fern  (aspidium);  (2)  areca  nut;  (3)  kusso; 
(4)  kamala.  Of  these  male  fern  is  particularly  serviceable.  Depending 
upon  the  weight  and  age  of  the  animal,  the  oleoresin  of  aspidium  may 
be  given  to  dogs  in  doses  of  fifteen  minims  to  one  dram.  It  can  be 
advantageously  combined  with  small  doses  of  areca  nut  (one  grain  per 
pound  of  body- weight) ,  and  conveniently  administered  in  capsule. 
Aspidium  should  never  be  given  with  oil  as  this  favors  its  absorption, 
and  it  is  a  local  action  which  is  sought.    After  three  to  four  hours  the 


T.ENIASIS  187 

dose  may  be  repeated,  and  twelve  hours  after  the  first  dose  a  purgative 
should  be  given. 

The  dog  should  be  kept  where  its  evacuations  can  be  conveniently 
examined,  and,  if  it  is  found  that  the  head  of  the  tapeworm  has  not  been 
expelled,  the  treatment  is  to  be  repeated  in  a  week  to  ten  days.  The 
expulsion  of  the  worm  may  be  aided  somewhat  by  rectal  injections  of 
warm  soapy  water. 

If  areca  nut  is  used  uncombined,  it  may  be  given  in  doses  of  two 
grains  for  each  pound  of  body-weight.  It  can  be  conveniently  adminis- 
tered shaken  up  in  a  little  milk.  Areca  nut  in  itself  is  laxative  or  purga- 
tive according  to  dosage.  If  purgation  has  not  followed  within  a  few 
hours  after  its  administration,  a  full  dose  of  castor  oil  should  be  given 
ten  to  twelve  hours  later. 

Kusso  has  an  advantage  in  being  quite  safe  even  in  excessive  doses. 
Small  dogs  take  of  the  fluid  extract  one-half  to  one  dram;  large  dogs, 
two  to  four  drams.  It  can  be  given  in  milk  and  repeated  three  times  at 
intervals  of  one  hour.  Vomiting,  which  sometimes  follows  the  adminis- 
tration of  kusso,  may  be  prevented  by  previously  giving  a  medicament 
having  an  anesthetic  action  upon  the  stomach. 

Kamala  is  given  to  dogs  in  doses  of  one-half  to  two  drams  in  honey  or 
syrup.  In  cases  where  heavj^  infestation  is  suspected  it  should  be  re- 
peated in  eight  hours.  Kamala  has  some  purgative  action  and  may 
also  nauseate;  the  latter  effect  can  be  corrected  by  the  same  means  as  for 
kusso. 

Other  taeniafuges  sometimes  used  are:  (1)  Pumpkin  seeds,  fed  crushed 
and  macerated  or  as  an  infusion,  and  (2)  turpentine,  one-half  to  one 
dram,  given  with  the  yolk  of  an  egg  and  repeated  mitil  three  doses  have 
been  administered  twenty-four  hours  apart.  Turpentine,  however,  on 
account  of  its  irritant  effect  upon  the  kidneys,  should  be  used  with 
caution. 

^^'hatever  form  of  taeniafuge  medication  may  be  chosen,  the  chances 
of  success  will  depend  much  upon  a  brisk  purgative  action  following 
upon  its  operation.  At  best  there  is  often  failure  to  secure  the  head  of 
the  worm,  in  which  event  a  repetition  of  the  whole  treatment  is  called 
for  in  the  course  of  one  to  several  weeks. 

Prevention. — To  prevent  the  spread  of  taeniasis,  all  expelled  tape- 
worms and  their  fragments  should  be  destroyed  by  burning.  Dogs 
known  to  be  infected  had  best  be  isolated  and  all  of  their  excrement 
burned.  Dogs  which  have  their  meat  cooked,  and  those  which  are  not 
allowed  access  to  the  viscera  of  slaughtered  animals  and  rabbits,  are 
not  so  likely  to  be  infected,  though  such  precautions  will  not  protect 
them  from  the  common  species  Dipylidium  caninum,  freedom  from  fleas 
and  lice,  and  prevention  from  association  with  dogs  less  fortunate  in 
this  respect,  being  essential  to  avoidance  of  infection  Iw  this  species. 


188  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Treatment  of  Taeniasis  of  the  Cat. — For  tseniasis  of  the  cat  the  same 
procedure  may  be  followed  and  the  same  remedies  used  as  for  the  dog. 
The  dosage,  however,  should  be  reduced  and  proportioned  according  to 
the  weight  and  age  of  the  animal. 

Prevention  consists  in  restraining  the  animals  from  feeding  upon 
rats  and  mice, — the  intermediate  hosts  of  their  most  common  tape- 
worm,— Tcenia  tceniceformis. 

Treatment  of  Taeniasis  of  Sheep  and  Goats. — For  several  days  pre- 
ceding treatment  of  these  animals  it  is  advisable  to  feed  moderately 
upon  green  succulent  food,  avoiding  bulk,  as  fodder  and  hay.  Imme- 
diately before  giving  the  vermifuge  all  food  should  be  withheld  for  a 
sufficient  time  to  make  the  animals  quite  hungry.  Powdered  areca  nut 
may  then  be  given  in  one  to  two  dram  doses  according  to  weight.  It 
can  be  administered  mixed  with  bran  or  bran  and  chopped  beets  which 
the  sheep,  made  ravenous  by  their  preliminary  fast,  will  eat  greedily. 
Three  hours  afterward  a  purgative  should  be  given  and  the  evacuations 
of  each  individual  kept  under  observation  for  the  appearance  of  tape- 
worms. 

Other  vermifuges  reconmi ended  are:  (1)  Oil  of  turpentine,  one  to  two 
drams,  given  in  one-half  to  one  ounce  of  linseed,  cottonseed,  or  olive 
oil,  and  (2)  kamala,  forty-five  grains  to  one  and  one-half  drams  in  thin 
syrup  or  water,  the  dose  to  be  repeated  once  at  an  interval  of  four  hours. 

Treatment  of  Taeniasis  of  Cattle. — Where  treatment  is  indicated  for 
the  expulsion  of  tapeworms  of  cattle  the  animals  should  be  dietetically 
prepared  as  recommended  for  sheep.  As  a  vermifuge,  tartar  emetic  is 
quite  suitable  for  these  animals.  It  may  be  given  in  one  and  one-half  to 
two  and  one-half  dram  doses  in  gruel.  Oil  of  turpentine,  three  ounces 
in  a  pint  of  linseed  oil,  makes  a  reliable  remedy.  Arsenic  in  daily 
ascending  doses  for  a  period  of  fifteen  days  has  also  been  recommended. 
The  vermifuge  treatment  should  be  followed  by  a  purgative  of  glauber 
salts. 

Treatment  of  Taeniasis  of  the  Horse. — The  existence  of  tapeworms 
in  the  horse  generally  remains  unrecognized  during  life.  The  symptoms 
are  those  general  to  intestinal  helminthiasis  of  horses,  and  the  treat- 
ment is  quite  the  same  as  that  for  ascariasis  (p.  234).  The  animal  is  to 
be  removed  from  work,  kept  from  hay,  and  fed  only  upon  mashes.  After 
at  least  twenty-four  hours  of  such  preparation,  give  two  to  four  ounces 
of  oil  of  turpentine,  and  one  dram  of  oleoresin  of  aspidium  in  a  pint  of 
linseed  oil.  Tartar  emetic  is  also  quite  effectual.  It  should  be  given 
in  two  doses  of  three  drams  each  at  an  interval  of  twelve  hours.  It 
may  be  mixed  with  a  gruel  of  linseed  meal. 


<^' 


CHAPTER  XVI 

TAPEWORMS   OF   CHICKENS 

Though  tapeworms  are  comparativelj'  frequent  in  chickens  and  other 
domestic  fowl,  they  have  not  up  to  quite  recent  times  been  the  subject 
of  anj'  considerable  investigation  in  this  country.  In  our  hterature  upon 
the  parasites  in  general,  if  not  neglected  entirely,  but  one  or  two  species 
are  as  a  rule  described,  and  these  generall}'  in  an  incomplete  manner. 

With  the  exception  of  but  one  species,  what  is  at  present  known  as 
to  the  larval  forms  has  been  determined  from  studies  upon  poultry 
cestodes  in  foreign  countries.  Thus  far  in  these  investigations  the  life 
C3'cle  of  but  one  chicken  tapeworm — Davainea  proglottina — has  been 
experunentally  demonstrated,  the  only  one  among  the  six  here  described 
which  has  not  been  reported  in  this  country.  The  remaining  five  have 
been  found  infesting  chickens  in  various  parts  of  the  United  States. 

1 .  Choanotaenia  inf undibulif ormis  iDrepanidotama  injimdi- 
buUformis)  (Fig.  102)— The  head  (Fig.  103)  is  small,  globular 
or  conical,  and  bears  a  crown  of  16-20  hooks.  The  suckers 
are  prominent,  may  be  projecting.  The  neck  is  very  short. 
The  first  segments  are  short;  those  following  are  infundibuli- 
form,  with  anterior  border  narrower  than  the  posterior.  The 
genital  pores  are  irregularly  alternate. 

The  length  varies  from  2-23  cm.  {%-^\^  inches). 

Grassi  and  Rovelli,  comparing  cysticercoids  which  they  had 
found  in  flies  (Musca  domestica)  with  the  adult  Choanotcenia 
inf undihidif ormis,  noted  a  stmctural  agreement  from  which 
they  inferred  that  the  larvae  were  the  intermediate  stage  of 
this  species.  No  experiments  were  carried  on  by  these  in- 
vestigators, however,  to  demonstrate  this  connection. 

Guberlet,  of  Oklahoma  Agricultural  and  Mechanical  Col- 
lege, in  a  series  of  investigations  upon  chicken  cestodes  (1912-  Fig.  102. 
1914)  seems  to  have  conclusively  demonstrated  that  the  ^nia^^'Jnl 
cysticercoid  of  Choanotcenia  infundihidiformis  occurs  in  the  fundibuli- 
common  house  fly.  Briefly  stated,  his  results  were  obtained  formis,  — 
by  raising  cysticercoids  in  the  flies  by  feeding  them  on  the 
eggs  of  the  tapeworm.  These  flies  were  fed  to  three  of  six  chicks 
which  had  been  removed  from  chance  infection  as  soon  as  hatched. 
Three  weeks  after  such  feeding  all  of  the  chicks  were  killed,  and  two  were 
found  to  be  infested  with  Choanotcenia  infundibuUformis.  The  three 
birds  used  as  a  check  on  the  experiment  contained  no  worms. 


190 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


2.  Hymenolepis  carioca. — The  head  is  piriform  with  retractile 
rostelhim.  It  is  unarmed.  The  segments  nmiiber  about  500,  all  much 
wider  than  long;  terminal  segments  measure  0.5-0.8  mm.  The  genital 
pores  are  unilateral.    The  worm  is  very  fragile  and  delicate. 

Length,  3-8  cm.  (1^-3  1/8  inches). 
The  life  history  is  unknown. 

3.  Davainea  tetragona( Tce/na  tetragona). — The  head  (Fig.  104)  is 
small  and  tetragonal;  rostellum  armed  with  a  crown  of  100  hooks.  The 
suckers  are  oval  and  armed  with  8-10  circlets  of  small  hooklets.  The 
short  neck  is  followed  by  short  trapezoid  segments,  those  terminal 


Fig.  103.— Choano- 
tsenia  infundibulifor- 
mis,  scolex  much  con- 
tracted,  —  enlarged 
(after  Guberlet,  in 
"Transactions  of  the 
American  Microscopi- 
cal Society"). 


Fig.  104.— Scolex  of 
Davainea  tetragona, — 
enlarged  (after  Guber- 
let, in  "Transactions 
of  the  American  Mi- 
croscopical Society".) 


Fig.  105. — Scolex  of  Davainea 
echinobothrida, —  enlarged  (after 
Guberlet,  in  "Transactions  of  the 
American  Microscopical  Society".) 


generally  longer  than  wide.  Their  length  varies  between  1-4  mm.  The 
genital  pores  are  unilateral. 

The  length  varies  between  1-25  cm.  (3/8-10  inches). 

Investigations  of  Plana  point  to  certain  little  snails  {Helix  carthu- 
sianella  and  H.  maculosa)  as  the  probable  larval  hosts  of  this  species. 

4.  Davainea  cesticillus  {Tmnia  cesticillus) . — ^The  head  is  globular 
and  has  a  rostellum  scarcely  salient  or  depressed.  It  is  armed  with  a 
double  crown  of  400-500  hooklets  which  are  loosely  attached.  The 
suckers  are  small  and  unarmed.  There  is  no  neck.  The  first  segments 
are  short  and  much  wider  than  the  head;  the  last  are  about  as  long  as 
broad.    The  genital  pores  are  irregularly  alternate. 

Length,  1-4.5  cm.  (3/8-1  3/4  inches).  By  some  authors  it  is  said  to 
attain  a  much  greater  length  (10-13  cm.). 


TAPE^YORMS  OF  CHICKENS  191 

According  to  Grassi  and  Rovelli  the  intermediate  host  is  a  lepidop- 
terous  or  coleopterous  insect. 

5.  Davainea  echinobothrida  (Tcenia  echinohotJirida). — The  small 
head  (Fig.  105)  presents  an  infundibulum  provided  with  a  double  crown 
of  about  200  hooks.  The  suckers  are  armed  with  8-10  circlets.  There 
is  no  neck.  The  segments  gradually  increase  in  Avidth,  the  largest  being 
1-4  mm.    The  genital  pores  are  irregularh'  alternate. 

Length,  5-25  cm.  (2-93^  inches). 

Nothing  is  known  of  its  larval  development. 

This  species  has  a  characteristic  pathological  effect  in  that  the  scolex. 
with  its  accessoiy  armature  about  the  suckers,  bores  through  the  in- 
testinal mucosa,  producing  large  nodules  or  ulcers.  The  condition  in 
fowls  is  termed  "nodular  tteniasis"  and  is  described  b}'  Moore  (Bureau 
of  Animal  Industry,  Cir.  No.  3,  1895).  The  nodules  are  often  mistaken 
for  other  diseases  showing  similar  features. 

6.  Davainea  proglottina  (Tcenia  proglottina) . — The  head  is  quad- 
rangular, slightly  rounded.  The  rostellum  is  armed  at  its  base  with 
80-95  hooks.  The  chain  is  composed  of  2-5  segments.  The  terminal 
and  largest  segments  have  a  tendency  to  detach  and  develop  separately 
in  the  intestine.  These  free  segments  maj-  acquire  a  length  exceeding 
that  of  the  entire  chain.    The  genital  pores  are  irregularly  alternate. 

Length,  0.5-1.55  mm. 

Grassi  and  Rovelli  have  demonstrated  that  the  larva  of  this  species 
is  a  cysticercoid  which  inhabits  several  species  of  snail — Limax  cinereus, 
L.  agrestis,  L.  variegatus. 

The  species  has  not  as  yet  been  reported  in  this  country. 

Occurrence. — Guberlet,  in  a  report  of  his  investigations  carried  on 
in  Nebraska  (Journal  of  the  American  Veterinary  INIedical  Association, 
]\Iay,  1916),  sets  forth  some  significant  data  as  to  the  prevalence,  in 
parts  of  the  LTnited  States  at  least,  of  chicken  cestode  infection.  Dining 
1912-13  he  examined  sixty-eight  birds  collected  mostly  from  Nebraska 
and  Illinois.  From  this  material  he  obtained  1,561  tapeworms,  specif- 
ically distributed  as  follows:  Davainea  tetragona,  598;  D.  cesticillus,  582; 
ChoanoUenia  infundibuliformis,  17Q;  Hymenolepsis  carioca,  154;  Davainea 
echinobothrida,  51 .  The  worms  were  present  in  numbers  per  host  varv-ing 
from  1-35.  (The  author  is  informed  by  Dr.  Guberlet  that  he  has  since 
found  as  many  as  115  in  a  single  animal.)  Most  of  the  birds  examined 
ranged  in  age  from  fouf  to  six  months. 

Symptoms. — As  a  rule  it  is  only  in  moderate  to  heavy  infection  that 
tapeworms  bring  about  morbid  conditions  in  fowl.  In  any  case  the 
symptoms  are  not  well  defined.  They  may  vary  in  different  individuals 
having  an  equal  degree  of  infestation,  age  especially  having  an  influence, 
young  birds  being  much  more  affected  than  adults  and  exhibiting  the 
sATiiptoms  more  definitely.    The  following  are  among  the  more  usual: 


192  PARASITES  OF  THE  DOMESTIC  ANIMALS 

There  is  an  abnormal  desire  for  food,  in  spite  of  which  the  heavih' 
infested  chickens  emaciate  and  become  anaemic,  as  manifested  by  pale- 
ness of  the  comb  and  wattles.  The  feathers  become  erect,  ruffled,  and 
dull,  and  the  birds  have  a  tendency  to  isolate  themselves,  often  in 
drooping  attitudes,  or  the  constantly  hungry  creatures  may  seem  never 
to  be  at  ease,  but  are  constantly  running  about,  this  probably  accounting 
in  part  for  the  loss  of  flesh.  In  such  aggravated  cases  there  is  often  ad- 
vanced emaciation,  and,  completely  exhausted,  the  bird  may  die. 

Diagnosis. — A  reliable  diagnosis  can  onl}^  be  made  by  finding  the 
segments  in  the  feces,  or  by  killing  and  examining  one  or  two  of  the 
birds  showing  suspicious  symptoms.  When  the  latter  method  is  adopted 
the  intestine  should  be  removed  and  slit  open  under  water.  After 
gentle  stirring  to  remove  the  contents,  it  may  be  transferred  to  a  basin 
of  clean  water,  when  the  worms,  if  present,  will  usually  be  seen  attached 
to  the  mucosa. 

Control. — As  in  other  forms  of  helminthiasis,  control  measures  are 
most  effectually  applied  to  the  parasites  in  their  stage  of  larval  develop- 
ment. Until  more  is  known  of  the  life  histories  of  the  chicken  tapeworms 
little  can  be  done  in  the  way  of  prevention  other  than  that  based  by 
analogy  upon  what  has  already  been  demonstrated.  It  is  scarceh' 
practical  to  keep  poultry  from  eating  such  possible  intermediate  hosts 
as  worms  and  insects.  Means  may  be  taken,  however,  to  restrict  their 
access  to  flies,  snails,  and  the  lower  crustaceans  of  stagnant  water, 
though  such  precaution  cannot  well  be  applied  to  birds  running  at  large. 
A  more  feasible  accessory  measure  is  the  prevention  of  the  larvae  from 
reaching  the  intermediate  hosts  by  isolating  the  infected  birds  in  screened 
quarters  where  their  droppings  may  be  collected  and  made  sterile  by 
burning  or  other  means. 

Treatment. — Vermifuges  may  be  administered  in  the  form  of  pills 
made  up  with  bread.  Probably  the  most  suitable  is  areca  nut  which 
can  be  given  to  adult  chickens  in  doses  of  from  ten  to  twenty  grains 
according  to  weight.  Young  animals  may  take  from  three  to  five 
grains.  After  three  days  the  treatment  should  be  repeated.  Other 
remedies  used  are  male  fern,  kamala,  turpentine,  and  pumpkin  seeds, 
the  dosage  being  proportionate  to  weight. 

Such  a  method  of  treatment  has  a  disadvantage  in  that  each  bird 
must  be  treated  individually.  Where  the  infection  occurs  in  large 
flocks  the  repeated  handling  of  each  bird  involves  such  an  amount  of 
time  and  patience  as  to  put  it  practically  out  of  the  question.  Again 
we  are  indebted  to  Guberlet  for  experiments  which  seem  to  point  the 
way  to  a  more  practical  method.  Bearing  upon  this  department  of  his 
work,  his  report  is  here  quoted  in  part. 

"Fifteen  birds  which  showed  symptoms  of  tapeworm  infection  were 
placed  in  a  cage  which  was  insect-proof  and  were  given  the  following 


TAPEWORMS  OF  CHICKENS  193 

treatment :  A  gallon  of  a  mixture  of  wheat  and  oats,  to  which  was  added 
a  small  tablespoonful  of  concentrated  Ij-e,  was  cooked  slowh'  for  about 
two  hours  and  allowed  to  cool.  The  birds  were  fasted  for  alDout  fifteen 
hours  and  were  then  given  as  much  of  the  mixture  as  they  would  eat, 
with  plenty  of  water.  Twelve  hours  later  one  of  the  birds  was  killed 
and  an  examination  of  the  small  intestine  was  made.  It  was  found 
that  nearly  all  of  the  worms  in  the  intestine  were  loose,  the  scolices  being 
detached  from  the  wall,  and  were  also  apparently  dead.  The  rest  of 
the  birds  were  given  a  second  dose  twenty-four  hours  after  the  first. 
INIan}'  worms  had  passed  with  the  droppings  in  from  twenty-four  to 
twenty-six  hours  after  the  first  feeding.  ^Nlost  of  the  worms  in  these 
droppings  were  dead,  but  in  all  probability  the  embryos  were  still  alive 
in  the  mature  proglottids.  Twelve  hours  after  the  second  dose  was 
given  another  bird  was  killed  and  it  was  found  that  only  a  few  worms 
were  left  and  all  of  these  were  detached  and  dead.  The  intestine  was 
filled  with  a  peculiar  gray-colored,  slimy  substance  composed  mainly 
of  mucus.  ]\Iany  entire  worms  and  fragments  were  passed  with  the 
droppings  during  the  period  of  feeding.  The  lye  acted  to  some  extent 
as  a  purgative. 

"The  birds  were  given  normal  diet  again,  and  in  a  few  daj's  they 
showed  no  s\nnptoms  of  infection.  Eight  days  after  the  second  dose  had 
been  given  two  more  birds  were  killed  and  examinations  made.  One 
possessed  a  small  fragment  of  a  tapeworm  and  the  other  was  entireh^ 
free. 

"This  remedy  has  been  known  to  many  poultry  raisers  for  some  time, 
but  they  have  neglected  to  use  it,  mainly  on  account  of  the  fact  that 
heretofore  no  definite  evidence  has  ever  been  presented  concerning  its 
actual  working  possibilities.  It  may  not,  and  in  all  probability  will  not, 
remove  all  of  the  worms,  but  it  does  remove  most  of  them  so  that  they 
are  not  serious  and  can  be  controlled  in  the  flock  as  a  whole." 


CHAPTER  XVII 


THE  TAPEWORM  LARV.E 


Certain  tapeworms  are  to  be  considered  as  to  their  pathogenicity 
from  two  important  points  of  view.  They  are  not  only  parasites  in  their 
adult  state  in  the  intestines  of  domestic  carnivores  and  man,  but,  in  the 
larval  stage  live  as  somatic  parasites  in  animals  used  as  food  by  man 
and  it  may  be  in  man  himself.  Depending  much  upon  their  numbers 
and  form  of  cyst,  these  cause  no  disturbance  to  their  host,  or,  through 
their  growth,  pressure,  and  inaccessibility,  may  constitute  a  menace  to 
health  far  more  serious  than  that  of  the  adult  worms  in  the  intestines. 

Three  forms  of  cestode  larvae  are  principallj^  concerned  in  this  connec- 
tion,— cysticercus  (Fig.  107),  coenurus  (Fig.  114),  andXechinococcus 
(Fig.  117).  A  brief  synoptical  arrangement  of  these,  including  the 
cysticercoid  and  plerocercoid,  follows: 

I.  Larva  having  a  caudal  vesicle.  Cystic 

A.  Larva  of  large  size.  Liquid  in  caudal 
vesicle  abundant.  Found  in  tissues 
and  closed  cavities  of  Herbivora  and 
Omnivora,  occasionally  in  Carnivora. 
1.  Vesicle  and  head  single,  i.  e.,  cyst 
monosomatic  and  monocephalic. 

Cysticercus 
{Cysticercus 
-pisiformis,   larva   of 
Tcenia  pisiformis) 


2.  Vesicles  multiple,  each  having  a 
single  head,  i.  e.,  polysomatic  and 
monocephalic. 


3.  Vesicles  multiple,  having  many 
heads  in  each,  i.  e.,  polysomatic 
and  polycephalic. 


Multiceps 

(Multiceps     multicepSf 
larva  of  M.  multiceps) 


Echinococcus 

(Echinococcus  granu- 
losus, larva  of  E, 
granulosus) 


THE  TAPEWORM  LARV^ 


195 


B.  Larva  small.     Little  or  no  liquid  in 
caudal  vesicle. 


1.  Larva  firm, 
like  process. 


terminating  in  a  tail- 


Cysticercoid 

{Monocercus  Davainece 
tetragonce,  larva  of 
Davainea  tetragona) 


Cryptocystis 

(Cryptocystis  tricho- 
dedes,  larva  of  Dipy- 
lidium  caninum) 


IL  Larva  without  caudal  vesicle. 

A.  Larva  worm-like.    Found  in  muscles 
of  fish. 

Plerocercoid 
(Larva  of 
DiphyUobothrium 
latum) 

Cysticercosis  (Measles) 

The  presence  of  cysticerci  in  the  connective  tissue  of  muscles  and 
other  parts  of  the  animal  organism  constitutes  the  condition  commonly 
known  as  measles  (cysticercosis).  The  disease  is  mainly  of  importance 
from  the  viewpoint  of  food  sanitation,  in  view  of  the  fact  that  measly 
beef  or  pork,  imperfectly  sterilized  by  cooking,  when  consumed  by  man, 
is  likely  to  infect  him  with  one  or  more  tapeworms. 

The  cysticerci  of  medical  interest  are,  in  their  order  of  frequency: 
Cysticercus  bovis  of  the  ox,  the  cystic  form  of  Tcenia  saginata  of  man, 
Cysticercus  ceUulosce  of  the  pig  (also  of  the  dog,  cat,  and  occasionally 
man),  the  C3^stic  form  of  Tcenia  solium  of  man,  and  Cysticercus  tenuicollis 
of  the  sheep  (occasionally  of  the  ox  and  pig),  the  cystic  form  of  Tcenia 
hydatigena  of  the  dog. 

For  the  development  and  structure  of  the  cysticerci  the  reader  is 
referred  to  the  Life  History  of  the  Taendiise  (p.  170). 


Measles  of  the  Ox 

Taenia  saginata  (T.  mediocanellata).  Fig.  106.  Tsniidae  (p.  170). — 
This  species,  commonly  known  as  the  beef  tapeworm,  of  which  Cysti- 
cercus bovis  is  the  larval  form,  lives  exclusively  in  the  intestine  of  man. 
The  head  (Fig.  109,  B)  is  small,  pear-shaped,  and  has  four  elliptical 
suckers  which  are  frequently  pigmented.  There  are  no  hooks,  and  in 
place  of  the  rostellum  there  is  a  sucker-like  depression.     The  neck  is 


196 


PARASITES  OF  THE  DOMESTIC  ANBIALS 


long  and  narrower  than  the  head.  The  segments,  which  may  nmnber 
from  one  thousand  to  one  thousand  three  hundred  or  more,  are  at  first 
much  wider  than  long.  The  complete  development  of  the  generative 
organs  occurs  at  about  the  six  hundredth  segment,  at  which  location 
the  segments  are  about  as  long  as  broad.  Segments  containing  the 
mature  embryos  reach  a  length  of  15-20  mm.  (5/8-3/4  of  an  inch)  and  a 
breadth  of  5-7  mm.  (1/4  -5/16  of  an  inch).  The  distal  margin  of  each 
segment  is  somewhat  swollen  and  surrounds  the  base  of  the  following 
segment.  The  genital  pores  are  irregularly  alternate  and  protrude  from 
the  margins  more  and  more  markedl}'  as  the  segments  approach  the 
distal  end  of  the  chain.  The  median  trunk  of  the  gravid  uterus  has 
twenty  to  thirtj'-five  delicate  lateral  branches  on  each  side,  and  these 
give  off  shorter  secondary  branches. 

The  length  of  the  entire  chain  may  be  from  3  to  12  meters  (9-38  feet), 
or  it  may  reach  a  much  greater  length. 


Fig.  106. — Taenia  saginata,  portions  of  adult, — natural  size  (after  Boas,  by  Kirkaldy 
and  Pollard,  from  Leuckart). 


The  eggs  (Fig.  110)  are  more  or  less  globular,  the  shell  frequently 
carrying  one  or  two  filaments.  As  found  in  the  feces,  the  eggs  often 
have  the  outer  shell  absent. 

Next  to  a  small  species — Hymenolepis  nana — this  is  the  most  common 
tapeworm  of  man  in  the  United  States,  and,  in  fact,  with  the  exception 
of  Diphyllohothrium  latum  in  a  few  districts,  is  the  most  prevalent 
species  infesting  man  in  other  parts  of  the  world.  It  is  not  found 
adult  in  other  animals,  and  its  cysticercus  lives  almost  exclusively  in 
the  ox. 

Occurrence  of  Beef  Measles. — That  the  beef  tapeworm  and  its  cj-sts 
(Cysticercus  bovis)  are  more  commonl}^  met  with  in  the  United  States 
than  the  pork  tapeworms  is  probably  due  to  the  fact  that  beef  is  more 
often  eaten  rare  in  this  countrj-  than  is  pork.  Beef  measles,  therefore, 
is,  in  its  relation  to  food  sanitation,  of  the  greater  importance.  Estimates 
made  upon  cattle  slaughtered  under  Federal  inspection  indicate  that 
nearly  one  per  cent,  of  all  the  cattle  slaughtered  in  the  United  States 


THE  TAPEWORM  LARV.E  197 

are  affected,  which,  m  addition  to  the  exposure  of  human  beings  to 
tapeworm  infection,  is  a  matter  involving  considerable  economic  loss 
in  the  condemnation  of  beef  otherwise  of  perfectly  good  food  value. 

When  it  is  considered  that  the  gravid  segments  of  the  beef  tapeworm 
each  contain  in  the  neighborhood  of  ten  thousand  eggs,  and  that  eight 
to  ten  of  these  segments  are  usually  passed  by  the  human  host  each  day, 
it  is  quite  evident  that,  under  certain  not  unusual  conditions,  the  in- 
fected person  could  be  responsible  for  the  presence  of  the  cj'sticerci  in  a 
large  number  of  cattle.  The  chances  for  such  transmission  will  be  in 
relation  to  the  location  and  habits  of  the  carrier  of  the  tapeworm.  If 
it  is  his  custom  to  defecate  about  stables  or  barnyards,  the  chance  that 
some  of  the  many  thousands  of  voided  embryos  will  reach  their  bovine 
hosts  is  obviously  much  increased.  Where  human  excrement  is  used 
for  soiling  without  its  first  having  been  made  non-infective  by  special 
treatment,  cysticercus  infection  among  cattle  and  hogs  is  especially 
frequent. 

Measles  is  more  often  found  in  young  than  in  aged  animals.  This  is 
probably  explained  by  the  fact  that  beef  animals  are  usually  slaughtered 
young  and  are  more  susceptible  to  infection  during  the  first  two  years  of 
their  life  when  the  tissues  offer  less  resistance  to  the  migration  of  the 
embrj'os.  In  aged  animals  the  cysts  are  likely  to  be  in  a  state  of  ad- 
vanced degeneration  or  entireh'  absorbed. 

Location  and  Appearance. — The  cysticerci  may  be  found  in  any 
organ,  but  are  more  especially  to  l^e  looked  for  in  the  interfascicular 
connective  tissue  of  striated  muscle  (Fig.  108).  Of  the  nmscles  invaded, 
the  first  to  be  mentioned  in  order  of  frequenc}^  are  those  of  mastication, 
chiefly  the  pterygoids  and  masseters;  following  these  are  the  heart — 
which  is  probably  as  frequently  infested  as  the  masticatory  muscles — 
the  muscles  of  the  neck,  intercostals,  and  muscular  portion  of  the 
diaphragm.  In  any  case  it  is  unusual  to  find  the  cysts  numerous  through- 
out the  muscle,  though  cases  occur  of  general  invasion  involving  most 
of  the  organs  of  the  body. 

The  size  and  appearance  of  the  cysts  vary  in  relation  to  their  age  and 
stage  of  development.  Experimental  infections  have  shown  that  in 
seventeen  to  twenty-five  days  they  measure  2-4  mm.  (3/32-3/16  of  an 
inch)  in  length  and  1.5-3  mm.  (1/16-1/8  of  an  inch)  in  breadth.  They 
are  grayish  white  in  color,  the  outer  connective  tissue  envelope  inclosing 
a  fluid  which  surrounds  the  clear  vesicle  or  bladder  worm.  This  is 
0.5-1.5  mm.  (1/32-1/16  of  an  inch)  in  diameter,  and  has  at  one  point  a 
yellowish  white  spot  indicating  the  location  of  the  invaginated  scolex 
which  will  evaginate  on  pressure  upon  the  vesicle. 

Experiments  by  Hertwig  have  demonstrated  that  the  cysts  become 
fully  developed  in  eighteen  weeks  after  the  occurrence  of  infestation. 
At  this  time  he  found  the  entire  dimensions  of  the  larger  cysts  to  be 


198 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Fig.    107. — Diagram    of 
Cysticercus. 


7  by  4.5  mm.  (9/32  by  3/16  of  an  inch),  while  those  of  the  bladder  were 

6  by  4  mm.  (1/4  by  3/16  of  an  inch). 

Degeneration. — After  a  period  of  time,  depending  somewhat  upon 

their  location,  the  cysticerci  undergo  caseous  degeneration  followed  by 

calcareous  infiltration.    That  these  changes  may 

set  in  early  has  been  shown  in  the  experiments 

of  Hertwig,  who  found  them  four  weeks  after 

infestation.  Commonly  the  degenerative  changes 

do  not  occur  until  full  development  is  reached  or 

for  some  time  after.     The  cysticerci  most  likely 

to  undergo  early  degeneration  are  those  located 

in    the  heart,   while  those  of  the  muscles  of 

mastication  probably  survive  the  longest.     If 

they  are  found  degenerated  in  the  latter  muscles, 

therefore,  it  is  not  likely  that  cysticerci  in  other 

parts  of  the  body  will  be  living  unless  they  are  from  a  later  infection. 
The  degenerated  cysts  may  be  recognized  by  their  yellowish,  or  some- 
times greenish  color.  They  may  be  semisolid  or  quite  gritty;  pus  may 
be  present  as  a  result  of  pyogenic  or- 
ganisms gathered  by  the  embryos  in 
their  migrations.  The  caseation,  how- 
ever, may  not  always  involve  the  para- 
site. In  such  cases  the  scolex  is  likely 
to  be  found  just  under  the  cyst  wall  with 
its  usual  characteristics  retained,  though 
the  caudal  bladder  is  apparently  absent. 
As  cysts  when  dissected  away  and  ex- 
posed to  the  air  tend  to  shrink  by  evapo- 
ration, their  structure  is  more  easily 
made  out  if  they  are  kept  moistened 
with  a  drop  or  two  of  water  during  the 
examination. 

Vitality. — The  cysts  of  beef  measles 
naturally   disintegrate    at   about   three 
weeks  after  the  death  of  the  host,  there- 
fore meat  kept  in  cold  storage  for  this 
Fig.  108.— Fragment  of  beef  mus-  period  will  not  be  likely  to  Contain  living 

cle,  showing  cysts   of  Cysticercus  larvse.     In  fresh   beef  all  will  be  killed 


bovis, — natural    size    (after    Neveu 
Lemaire,  from  Railliet). 


by  the  apphcation  of  sufficient  heat  (60- 
70°  C.  =  140-156  F.)  to  cook  the  meat 
until  its  cut  surface  presents  a  uniform  gray  color  throughout.  Freezing 
for  a  number  of  days  will  destroy  them,  but  this  method  has  a  disad- 
vantage in  that  decomposition  of  the  meat  follows  rapidly,  making  it 
necessary  that  it  be  quickly  used.     Based  upon  experiments  by  Ran- 


THE  TAPEWORM  LARV.E 


199 


som  relative  to  this  method,  Federal  meat  inspection  regulations  provide 
that  beef  carcasses  showing  a  slight  degree  of  infestation  may  be  passed 
for  food  if  held  for  six  days  at  a  temperature  not  exceeding  15°  F. 
(-9.44°  C),  as  an  alternative  to  the  requirement  of  retention  for  twenty- 
one  days. 

Symptoms. — Symptoms  in  bovine  measles  are  practically  nil.  There 
is  rarely  a  history  of  disturbance  from  the  presence  of  the  cysts,  and  it  is 
extremely  exceptional  for  the  condition  to  be  recognized  before  the 
animal  is  slaughtei-ed. 

Measles  of  the  Pig 

Taenia  solium. — Tieniidae  (p.  170).  This  species,  to  which  Cysticercus 
cellulosce  gives  rise,  also  lives  in  the  human  intestine  and  is  commonly 
referred  to  as  the  pork  or  armed  tapeworm.  It  is  smaller  than  T.  sag- 
inata.    The  head  (Fig.  109,  A)  is  glolnilai'  and  loss  than  I  mm.  in  diam- 


Fn;.  109. — "Head"  of  Taenia  solium  (A),  of  T.  saginata  (B),  and  Diphjl- 
lobothrium  latum  (C).     (After  Boas,  by  Kirkaldy  and  Pollard). 

eter;  the  rostellum  is  short  and  provided  with  a  double  crown  of  hooks. 
The  neck  is  long  and  slender.  The  first  segments  are  very  short,  grad- 
ually increasing  in  length  and  lireadth.  At  about  one  meter  (39  inches) 
from  the  head  they  are  as  long  as  broad  and  have  the  generative  organs 
fulh'  developed.  Toward  the  distal  end  of  the  chain  they  measure  10- 
12  mm.  (3/8-1/2  an  inch)  in  length  and  5-6  mm.  (1/4  of  an  inch)  in 
breadth.  The  total  number  of  segments  is  fi-om  800  to  900.  The  genital 
pores  are  more  i-egularly  alternate  than  in  T.  saginata.  The  median  trunk 
of  the  gravid  uterus  has  7  to  12  ti'oe-like  lateral  branches  on  each  side. 


200 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


The  entire  length  of  the  worm  is  2-3  meters  (6-9  feet),  though  it 
may  be  longer. 

The  eggs  (Fig.  110)  are  oval  and  provided  with  a  very  delicate  shell. 
The  shell  surrounding  the  onchosphere  is  globular  and  thick. 

This  tapeworm  is  much  more  rare  in  the  United  States  than  is  T. 
saginata.  In  general,  its  distribution  may  be  said  to  correspond  Avith 
that  of  the  domestic  pig,  correlated  with  the  custom  of  eating  the  flesh 
of  this  animal  raw  or  unperfectly  cooked.  The  cysticercus  not  only 
infests  the  pig,  but  may  find  lodgment  in  man  himself  if  the  eggs  from 
an  adult  worm  infesting  his  intestine  find  their  way  to  his  stomach. 


Fig.  110.— Egg  of  Tsenia 
saginata,  with  outer  shell  and 
filaments;  embryo,  with  em- 
bryonal shell,  in  center.  Egg 
of  T.  solium  (above),  show- 
ing embryo  with  embryonal 
shell. 


Fig.  111. — Mature  segment  of  Taenia 
saginata  (left)  and  T.  solium  (right) ,  showing 
laterally  branched  uterus. 


For  this  reason,  with  the  added  one  that  the 
larvae  may  become  established  in  the  central 
nervous  system  or  eye,  Tcenia  solium  consti- 
tutes a  much  more  serious  infestation  than 
does  T.  saginata. 

A  simple  method  for  determining  to  which 
of  these  two  species  the  infecting  tapeworm 
belongs  consists  in  clearing  up  a  voided  segment,  pressing  it  between 
two  clean  slides,  and  observing  the  form  of  the  gravid  uterus  as  the 
specimen  is  held  before  a  strong  light.  If  the  median  trunk  shows 
numerous  delicate  lateral  branches  on  each  side  (20-35)  it  indicates 
that  the  infection  is  with  Tania  saginata.  If  these  branches  are  less 
numerous  (7-12)  and  more  robust,  it  may  be  concluded  that  the  seg- 
ment belongs  to  T.  solium  (Fig.  111). 

If  treatment  has  resulted  in  the  expulsion  of  the  entire  worm,  an 
exact  differentiation  can  be  made  by  examination  of  the  head  under  low 
power  magnification.  The  pork  tapeworm  will  show  the  cephalic  arma- 
ture which  in  the  beef  tapeworm  is  absent. 

Occurrence  of  Pork  Measles. — While  the  larvse  of  the  unarmed 
tapeworm  of  man  live  only  in  cattle,  those  of  the  armed  tapeworm  may 


THE  TAPEWORM  LARV.E 


201 


develop  in  almost  an}-  mannnal  to  which  the}'  find  access.  The  hog, 
however,  is  the  most  common  host,  and,  from  the  point  of  view  of  public 
health,  the  most  important. 

As  has  been  noted,  the  cysticercus  of  Tcenia  solium  (Cysticercus  cel- 
lulosce)  is  a  more  dangerous  parasite  than  that  of  T.  saginata,  as  it  may- 
lodge  in  organs  such  as  the  brain  or  eye  with  serious  consequences. 
Man  can  readily  become  a  victim  by  auto-infection  from  his  own  armed 
tapeworm,  the  eggs  of  which  may  reach  his  stomach  by  way  of  the 
pyloris,  or  in  being  conveyed  to  the  mouth  by  unclean  fingers.  By  the 
latter  means,  moustache  twirlers  and  nail  biters  are  especially  exposed. 

Fortunatel}',  the  United  States  is  favored  by  the  rarity  of  the  pork 
tapeworm  and  consequently  its  cysts.    Pig  measles  is  most  prevalent  in 


Fig.  112. — Stages  in  tapeworm  larval  development:  a,  six-hooked  larva  K;"| 
(hexacanth  or  onchosphere)  of  Taenia  solium;  b,  cystic  stage  of  same;  c,  same  p-.^ 
with  head  evaginated;  d,  ciliated  larva  of  Diphyllobothrium  latum;  e,  plero-  \J 

cercoid  of  same — all  enlarged  (after  Boas,  by  Kirkaldy  and  Pollard,  from 
Lcuckart). 

districts  of  foreign  countries  where  Ijad  hygienic  conditions  pi-evail; 
where  pigs  are  kept  near  dwellings,  and  their  flesh  is  eaten  raw  or  im- 
perfectly cooked,  conjoined  with  the  practice  of  depositing  human 
excrement  in  the  open  or  spreading  it  upon  the  fields  as  fertihzer.  In 
countries  where  sanitary  control  is  of  a  more  advanced  standard  the 
prevalence  of  the  ])ork  tapeworm  has  been  greatly-  reduced. 

Location  and  Appearance. — The  muscles  most  often  invaded  by  the 
cysts  are  those  of  the  tongue,  neck,  and  shoulder,  then,  in  order  of 
frequencA',  the  intercostals,  abdominal,  psoas,  the  muscles  of  the  thigh, 
and  those  of  the  posterior  vertebral  region.  Organs  less  often  infested 
are  the  liver,  kidneys,  heart,  lungs,  brain  and  eye. 

While  the  cysts  may  be  scattered  and  few  in  number,  the}^  are,  on 
the  other  hand,  sometimes  present  in  certain  locations  in  enormous 
numbers.     Kuchenmeister  in  one  case  found  one  hundred  and  thirtA'- 


202  PARASITES  OF  THE  DOMESTIC  ANIMALS 

three  in  a  piece  of  meat  weighing  seventeen  grammes  (260  gr.), — propor- 
tionately eight  thousand  per  kilogramme  (2  lbs). 

More  delicate  and  transparent  than  those  of  beef  measles,  the  cysts 
are  elliptical  in  form,  6-15  mm.  long  by  5-10  mm.  broad  (1/4-5/8  by 
7/32-3/8  of  an  inch).  The  wall  enveloping  the  vesicle  is  a  thin  semi- 
transparent  connective  tissue  membrane  which,  in  loose  connection  with 
the  surrounding  tissue,  when  removed,  leaves  a  reddened  alveolar  pit. 
Pressure  upon  the  caudal  vesicle  causes  the  evagination  of  the  larval 
head  which,  on  examination  by  low  magnification,  is  seen  to  be  te- 
tragonal and  to  possess,  in  addition  to  the  four  suckers,  a  double  crown 
of  twenty-two  to  thirty  hooks, — characters  defining  it  as  the  larval 
head  of  Tcenia  solium. 

At  about  twenty  days  from  infestation  the  cyst  shows  as  a  delicate 
vesicle  about  the  size  of  a  pin  head,  with  the  rudimentary  head  indicated 
by  a  cloudy  point,  and  as  yet  without  enveloping  connective  tissue  mem- 
brane. At  the  age  of  one  hundred  and  ten  days  all  of  the  cysts  are 
approximately  of  equal  size;  the  scolex  is  developed  and  lies  invaginated 
into  the  caudal  bladder.  When  located  in  organs  such  as  the  lungs, 
liver,  and  spleen,  they  often  appear  as  grayish,  caseous,  calcareous,  or 
purulent  nodules  somewhat  reseml^ling  those  of  tuberculosis.  Differen- 
tiation can  be  made  by  careful  examination  which  will  reveal  the  hooks 
and  often  the  larval  heads. 

In  some  cases  a  diagnosis  can  be  made  while  the  animal  is  still  living 
Ijy  examination  of  the  inferior  surface  of  the  tongue.  If  cysts  are  present 
in  that  organ,  they  will  be  near  the  base  and  at  the  sides  of  the  frsenum, 
where  they  may  be  seen  as  semi-transparent,  round  or  oval  vesicles 
protiiiding  beneath  the  mucous  membrane. 

Degeneration. — Degeneration  of  the  cysts  may  begin  at  any  stage 
of  their  development,  though  those  in  the  visceral  organs  are  the  first  to 
undergo  these  changes.  The  process  begins  Avith  the  connective  tissue 
envelop  and  later  involves  the  scolex.  The  caseous  cysts  present  a 
gray  color,  while  those  which  have  become  calcified  are  white.  In  the 
older  degenerated  cysts  the  changes  have  advanced  to  transformation 
into  small  calcareous  bodies  without  fluid,  constituting  the  "dry 
measles  "  as  termed  by  the  butcher.  In  such  cases  the  larvae  are  un- 
doubtedly dead. 

Vitality. — The  cysticercus  of  pork  measles  is  slightly  more  resistant 
to  heat  than  is  that  of  beef  measles.  Under  post-mortem  conditions  it 
survives  much  longer.  Ostertag  found  living  larvge  in  pork  forty-two 
days  after  it  had  been  slaughtered.  Preservation  in  cold  storage  as  for 
beef  measles,  therefore,  will  not  be  efTe.ctual.  All  cysts  will  be  rendered 
harmless  if  the  pork  is  cooked  until  its  cut  surface  presents  a  uniformly 
whitish  color. 

Symptoms. — Ordinarily  measles  of  the  pig.  as  in  the  ox,  presents 


THE  TAPEWORM  LARV.E  203 

no  recognizable  symptoms,  and,  unless  the  cysts  can  be  seen  beneath 
the  visible  mucous  membranes,  the  condition  is  only  observed  post- 
mortem. If  the  cysticerci  become  lodged  in  nerve  centers,  there  may  be 
such  manifestations  as  circling  movements,  grinding  of  the  teeth,  or, 
possibly,  convulsions  and  opisthotonos;  symptoms  which  can  no  more 
than  suggest  measles  as  a  possible  cause.  ^       /     ^^\/Uf^,    !  ' 

Measles  of  the  Sheep 

Tcenia  hydatigena,  of  which  Cysticercus  tenuicollis  of  the  sheep  is  the 
larval  form,  has  been  described  under  Cestodes  of  the  Dog  (p.  178). 

Occurrence. — Cysticercus  tenuicollis  has  its  development  under  serous 
membranes  of  the  sheep  principally,  but  it  may  also  appear  in  other 
ruminants  and  in  the  pig.  Infestation  is  by  food  and  water  bearing 
ova  which  have  been  spread  about  by  dogs  harboring  the  adult  worm. 

Experiments  have  shown  that  the  majority  of  the  embryos  reach  the 
peritoneal  cavity  by  way  of  the  liver.  Ten  days  after  infestation  tor- 
tuous hemorrhagic  trails  may  be  found  upon  the  surface  of  this  organ 
under  the  capsule  of  Glisson.  These  are  produced  by  the  migrations  of 
the  parasites,  and  are  in  close  relation,  usually  at  their  extremities,  with 
vesicles  0.5-3.5  mm.  in  diameter.  The  head  is  fully  developed  about 
the  fortieth  day,  and  the  vesicle  reaches  its  full  growth  at  about  the 
seventh  month,  when  it  may  have  a  diameter  of  1.5-5  cm.  (5/8-2  inches), 
often  about  the  size  and  form  of  a  pigeon's  egg. 

These  cysts  ("water-balls")  may  be  found  in  var>'ing  numbers,  their 
size  and  location  depending  upon  the  age  of  the  infestation.  Their 
seat,  especially  in  young  animals,  is  usually  beneath  the  serous  capsule 
of  the  liver,  though,  particularly  in  old  infestations,  large  bladders  may 
])e  found  in  most  any  part  of  the  peritoneal  cavity. 

As  it  relates  to  food  sanitation,  this  cysticercus  of  sheep  is  of  little 
importance.  The  location  and  size  of  the  cysts  render  them  easy  of 
elimination  from  parts  used  as  human  food. 

As  a  mattei-  of  control,  it  is  obvious,  in  reference  to  the  life  history  of 
the  tapeworm,  that  offal  containing  such  cysts  should  be  inaccessible 
to  dogs. 

Symptoms. — Sheep  measles  can  rarely  be  recognized  until  after  the 
death  of  the  animal. 

Cysticercus  ovis. — Muscular  cysticercosis  in  sheep  has  been  shown 
by  investigations  within  the  past  few  years  to  be  more  common  than 
had  been  suspected.  It  has  been  determined  by  Ransom  that  the 
cysticercus  is  derived  from  a  tapeworm  having  its  adult  development  in 
tiie  dog,  and  not  to  a  tapeworm  of  man  as  had  been  supposed. 

The  following  data  in  regard  to  this  form  of  measles  are  quoted  from 
Hall  (Bulletin  No.  260,  U.  S.  Dept.  of  Agriculture): 


204  PARASITES  OF  THE  DOMESTIC  AXI^LVLS 

"Ransom's  investigations  showed  that  under  careful  inspection  the 
percentage  of  afTected  sheep  in  this  countrj-  has  amounted  to  two  per 
cent,  or  more,  and  that  approximately  twenty  thousand  sheep  carcasses 
were  retained  in  1912  in  abattoirs  under  Federal  inspection  on  account 
of  sheep  measles  due  to  this  parasite. 

''The  bladder  worm,  Cysticercus  ovis,  in  the  meat  of  sheep  is  oval  and 
ranges  in  size  from  about  one-third  of  a  centimeter  (one-eighth  of  an 
inch)  to  almost  a  centimeter  (three-eighths  of  an  inch)  in  length.  Inside 
of  this  bladder  there  is  a  single  tapeworm  head,  in  which  respect,  as  well 
as  in  size,  this  cysticercus  differs  from  a  hydatid  or  a  coenurus.  Numer- 
ous C3'sts,  however,  may  be  scattered  through  the  musculature,  so  that 
in  their  numbers  there  is  a  compensation,  so  to  speak,  for  their  small 
size  and  lack  of  multiplicity'  of  heads.  Inasmuch  as  the  presence  of  these 
cj'sts  calls  for  condemnation  of  a  part  or  all  of  the  infested  carcass,  ac- 
cording to  the  degree  of  the  infestation,  and  the  number  of  carcasses 
amounts  to  twenty  thousand  a  year,  this  parasite  has  considerable 
economic  interest  for  this  countiy,  and  never  more  than  at  the  present 
time  when  the  "high  cost  of  living"  is  such  a  vital  topic. 

"When  one  of  these  cysticerci  from  mutton  is  ingested  by  a  dog,  the 
tapeworm  head  passes  undigested  to  the  dog's  intestine  and  develops 
into  a  fairh'  large  tapeworm,  comparable  to  the  gid  tapeworm.  Sim- 
ilarly, this  tapeworm,  Toenia  ovis,  produces  eggs  which  are  passed 
out  with  the  feces  of  the  dog,  and  which  are  ingested  by  sheep  as 
they  graze  over  range  or  pasture  or  drink  water  contaminated  by  these 
feces, 

"The  parasite  has  been  found  in  Europe,  Africa,  and  New  Zealand. 
It  has  been  found  thus  far  in  seven  States  in  this  country.  It  appears 
to  be  particular!}^  prevalent  in  the  AVest,  a  fact  that  is  possibly  related 
to  carelessness  on  the  part  of  the  western  sheepmen  as  regards  disposal 
of  carcasses  of  sheep  d^dng  on  the  range." 

Control. — ^Measures  of  prevention  consist  in  restraining  dogs  from 
access  to  the  flesh  of  affected  sheep  unless  it  is  rendered  non-infective 
by  cooking.  Homeless  dogs  should  be  destroyed,  and  others  going 
about  where  their  excrement  may  contaminate  the  food  and  water  of 
sheep  should  be  kept  free  from  tapeworms  as  a  precuation,  not  only 
against  this,  but  other  tapeworm  larvae  infesting  sheep. 

CcExuRosis,  Gid 

Gid,  turnsick,  or  staggers  are  popular  terms  applied  to  a  disease  of 
the  brain  or  spinal  cord,  caused  by  the  presence  in  these  locations  of 
the  gid  parasite  Midticeps  multiceps  {Ccenwnis  cerebralis),  the  coenurus 
or  larval  stage  of  the  tapeworm  of  the  dog  Multiceps  multiceps,  Fig.  113 
(p.  179). 


THE  TAPEWOR^I  LARA\E 


205 


It  is  observed  most  often  in  sheep,  more  rarely  in  cattle,  goats,  and 
other  ruminants.    It  has  been  reported  in  the  horse. 

Occurrence. — Gid  is  a  common  disease  in  Europe  where  it  has  l)een 
known  for  mam-  j-ears.  The  parasite  has  been  observed  in  this  country 
at  least  as  early  as  1901,  though  symptoms  which  were  undoubtedly 
those  of  gid  were  authentically  reported  from  our  far  western  fiocks 
during  at  least  ten  years  preceding. 
In  1909  Taylor  and  Bo^^lton  found 
an  outbreak  in  a  flock  of  sheep  about 
forty  miles  from  Ithaca,  New  York. 
Necropsies  in  these  cases  revealed 
the  presence  of  the  gid  parasites 
from  which,  by  feeding  to  dogs, 
they  claim  to  have  raised  the  adult 
tapeworm.  This  is  the  first  authen- 
tic instance  of  gid  in  the  Eastern 
United  States,  and  the  first  account 
of  it  was  given  by  Dr.  James  Law, 
of  Cornell  University,  in  a  paper 
read  before  the  New  York  State 
Veterinar>^  Medical  Society'  in  the 
same  year. 

In  view  of  the  large  number  of 
sheep  and  dogs  which  have  been 
brought  to  the  United  States  from 
countries  where  gid  prevails,  it  is 
somewhat  remarkable  that  the  dis- 
ease has  not  been  more  often  ob- 
served here.  It  is  probable  that  nu- 
merous cases  have  occurred  which 
have  passed  unrecognized  and  con- 
sequently unrecorded,  the  SAaiiptoms  Fig.  113.— Portions  of  adult  gid  tape- 
being  ascribed  to  other  causes.      It  is    worm  (Multiceps  multiceps), — natural  size 


(after  Ransom,  from  Railliet,  Bull.  Xo.  ^ 
Bureau  An.  Ind.,  U.  S.  Dept.  of  Agr.). 


certain  that  it  now  has  a  foothold  in 
this  country,  in  view  of  which  fact, 
and  the  further  one  that  in  other  countries  it  is  one  of  the  most  de- 
structive parasitic  diseases  of  sheep,  veterinarians  and  sheep  raisers 
should  be  on  the  lookout  for  it  and  take  proper  preventive  precautions. 
The  Coenurus. — The  completely  developed  coenurus  (Figs.  114  and 
116)  consists  of  a  membraneous  vesicle  which  may  vary  in  size  from  that 
of  a  hazelnut  to  that  of  a  hen's  egg.  When  located  on  the  brain  it  tends 
to  assume  a  spherical  form;  when  on  the  cord,  which  is  more  rare,  it 
becomes  adaptively  elongated.  The  wall  is  thin,  translucent,  and  dis- 
tended by  a  colorless  fluid.    On  the  surface  of  the  vesicle  there  are  little 


206 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


white,  irregTilarh'  grouped  spots,  each  representing  an  invaginated  larval 
tapeworm  head.  These  vary  in  degree  of  development  and  in  nmnber 
from  four  hundred  to  five  hundred,  and  herein  lies  an  essential  differ- 
ence between  coenurus  and  cj-sticercus,  the  latter  containing  but  one 


Fig.  114. — Diagrammatic  section  of  C'cx'iiuius:  a,  normal  dis- 
position of  scolex;  b,  c,  d,  e,  diagrammatic  representation  to  show 
the  homology  between  cysticercus  and  coenurus  (after  Ransom, 
from  Railliet,  Bull.  No.  66,  Bureau  An.  Ind.,  U.  S.  Dcpt.  Agr.). 


Fig.  115. — Brain  of  lamb,  showing  the  furrows  pro- 
duced by  the  migration  of  the  young  gid  bladderworms, 
taken  at  a  time  immediately  following  the  period  of 
invasion — i.  e.,  from  fourteen  to  thirtj'-eight  days  after 
infestation, — natural  size  (after  Ransom,  from  Leuck- 
art,  Bull.  No.  66,  Bureau  An.  Ind.,  U.  S.  Dept.  Agr.). 


Ik  IK)  (  id  b!  iddciworm 
■^ho^Mng  niimatuic  tapeworm 
heads, — natural  size  (after 
Ransom,  from  Railliet,  Bull. 
No.  66,  Bureau  An.  Ind.,  U.  S. 
Dept.  Agr.). 


head.  In  some  cases  the  heads  may  be  found  evaginated  to  the  surface 
of  the  vesicle  (Davaine),  when  the  cerebral  disturbance  by  pressure  is 
contributed  to  by  the  direct  irritation  from  the  booklets. 

Development. — Animals  susceptible  to  gid  become  infested  by  eggs 
of  the  tapeworm  Midticeps  multice'ps  which  is  harbored  by  dogs.  The 
eggs  and  gravid  segments,  spread  about  as  they  are,  will,  in  the  presence 


THE  TAPEWORM  LARV.E  207 

of  moisture  and  favorable  temperature,  retain  their  power  to  infect 
for  several  weeks.  In  dry  locations  and  under  the  influence  of  a  hot 
sun  the  period  of  their  vitality  is  reduced,  probably  to  a  few  days  at 
most.  Eggs,  through  the  mediation  of  food  and  water,  reaching  the 
digestive  juices  of  sheep  and  cattle  have  their  shells  dissolved,  setting 
free  the  contained  eml^ryos  which,  on  reaching  the  intestine,  penetrate 
its  walls  by  means  of  their  booklets.  From  here  it  is  probable  that  they 
are  passively  carried  to  other  parts  of  the  body  by  the  blood  and  hnnph 
currents.  With  rare  exception,  only  those  embryos  which  reach  the 
brain  or  spinal  cord  continue  their  development. 

The  central  nervous  system  is  reached  by  the  embryos  about  the 
eighth  day  after  the  occurrence  of  infection,  upon  the  arrival  at  which 
location  they  lose  their  booklets  and  transform  into  small  cysts.  In  the 
course  of  their  burrowings  along  the  surface  of  the  brain  they  leave 
small  sinuous  tracks  which  may  be  found  three  to  five  weeks  after  in- 
fection, often  marked  by  a  yellowish  purulent  material  (Fig.  115).  At 
the  termination  of  these  furrows  the  young  bladderworms  become 
stationaiy,  and  their  development  proceeds. 

In  five  to  six  weeks  the  cysts  are  about  1  cm.  (3/8  of  an  inch)  in  diam- 
eter and  the  heads  have  begun  to  appear,  these  attaining  their  full 
development  in  ten  to  thirteen  weeks.  The  cj'sts  continue  to  grow 
until  they  have  reached  a  diameter  of  from  3  to  5  cm.  (1  3/16  to  2  inches), 
during  which  time  new  heads  are  in  process  of  formation  (Fig.  116). 
Heads  in  various  stages  of  development,  therefore,  may  be  found  in  the 
same  vesicle. 

Tabular  Review  of  Life  History  of  Multiceps  Multiceps 
Adult  Tapeworm  in  intestine  of  dog. 

Egg. — Expelled  from  intestines. 

Hexacanth. — Freed  from  egg  in  digestive  tract  when 

I  ingested  by  sheep. 

Acephalocyst  — In  brain  or  cord  of  sheep. 

Coenurus  (Polycephalic  cyst). — Same. 

Scolex. — Attached  to  intestinal  wall   of  dog  after  in- 

I  gestion  of  cyst. 

Adult  Tapeworm. — In  intestine  of  dog. 

Post-mortem  Appearance. — In  chronic  cases  there  are  usually  one 
or  more  cysts,  rarely  as  many  as  six,  though  cases  are  recorded  in  which 


^208  PARASITES  OF  THE  DOMESTIC  ANIMALS 

there  were  more  than  twice  this  number.  The  lesions  produced  will 
differ  according  to  the  development  attained  by  the  parasites  at  the 
time  of  the  examination.  Primarily  the  lesions  are  disseminated,  and 
the  small  cysts  may  be  found  at  various  places  upon  the  convex  surface 
of  the  brain,  surrounded  by  a  yellowish  exudate,  granules,  and  cal- 
careous particles,  while,  in  the  vicinity,  there  may  be  a  small  hem- 
orrhagic area.  In  cases  which  have  presented  the  characteristic  symp- 
toms of  turnsickness,  or  gid  properly  so-called,  but  one  large  vesicle  of 
advanced  development  is  ordinarily  found  (Fig.  116).  Such  cysts  are 
usually  located  upon  the  surface  of  the  cerebral  hemisphere,  where, 
by  their  pressure,  they  produce  an  ansemia  and  softening  of  the  cortical 
substance.  In  old  cases  with  large  cysts  situated  upon  the  brain's  sur- 
face the  constant  compression  upon  the  roof  of  the  cranium  may,  by 
absorption,  bring  about  thinning  of  the  bone  to  such  a  degree  that  it 
will  yield  to  even  comparatively  slight  pressure  of  the  fingers. 

Exceptionally,  the  coenurus  may  be  found  free  in  an  excess  of  fluid 
in  a  lateral  ventricle,  and,  again  rarely,  exploration  of  the  vertebral 
canal  will  reveal  a  cyst  in  the  lumbar  or  cervical  region,  or  it  may  be 
at  the  medulla  oblongata.  Such  cysts  are  much  elongated,  and  usually 
there  is  but  one.  At  the  cyst's  location  the  medullary  substance  is 
atrophied  and  softened.  Such  muscles  as  may  be  secondarily  involved 
show  the  alterations  of  atrophy  and  cachexia. 

Symptoms. — As  may  be  inferred  from  the  foregoing,  the  symptoms 
presented  in  coenurosis  will  be  conditional  upon  the  age  of  the  infection 
and  the  size  attained  b}^  the  cysts,  and  also  upon  their  location,  the 
latter  factor  furnishing  the  two  forms  of  the  affection, — the  cephalic, 
when  located  in  the  brain,  and  the  medullary  if  in  the  vertebral  canal. 

If  the  parasites  are  few  in  number,  there  will  be  no  symptoms  during 
the  early  stages,  or  the^^  may  be  slight  and  unnoticed.  If  there  is  a 
heavy  invasion  the  cerebral  disturbances  caused  by  the  migrations  of  the 
parasites  may  be  manifested  as  stated  below.  According  to  Moller, 
however,  these  primary  symptoms  are  not  observed  in  four-fifths  of 
the  cases. 

Early  in  the  infestation  there  is  dullness,  somnolence,  inappetence, 
and  usually  a  rapid  loss  of  flesh.  Visual  disturbance  is  soon  noticed,  the 
animal  colliding  with  objects  which  it  is  apparently  unable  to  see. 
Examination  of  the  eyes  at  this  time  will  show  a  congestion  of  the 
sclera;  later  there  is  strabismus  with  either  convergence  or  divergence, 
and  the  pupils  may  be  unequally  dilated.  There  are  concomitant 
troubles  of  motility,  and,  as  the  disease  progresses,  the  animal  frequently 
falls  down  or  may  assume  a  recumbent  position  for  the  entire  day. 
If  it  becomes  unable  to  rise,  it  is  probable  that  death  will  soon  follow. 

When  these  early  symptoms  occur,  they  generally  first  appear  ten 
to  twenty  days  after  infection  and  persist  for  a  variable  period  of  two 


THE  TAPEWORM  LARV.E  209 

to  ten  days.  The}-  then  subside,  and,  during  a  following  latent  period 
of  four  to  six  months,  it  is  only  by  close  observation  that  anything 
abnormal  about  the  animal  can  be  detected.  The  ocular  disturbances 
already  referred  to  then  appear;  the  head  is  held  in  a  peculiar  position, 
and  the  animal  turns  in  circles  or  it  ma^'  stagger  and  stumble  about, 
repeatedly  falling.  The  movements  are  made  in  an  impulsive  manner, 
with  feet  lifted  high,  and  the  turning  may  be  to  the  right  or  to  the  left, 
usually  toward  the  side  on  which  the  brain  is  compressed.  Other  move- 
ments than  turning  may  be  exhibited,  and,  in  fact,  their  character  will 
depend  upon  the  part  of  the  brain  affected  by  the  cyst. 

These  s^inptoms  are  not  continuous,  appearing  several  times  during 
the  day  with  intervals  of  comparative  repose.  In  three  to  six  weeks 
from  their  onset  the  animal  passes  into  a  state  of  complete  paralysis 
and  dies  from  exhaustion,  or  it  may  be  in  convulsions. 
•  Such  characteristic  phenomena  of  gid  are  of  the  final  stage,  and  are 
due  to  the  pressure  of  the  fully  developed  coenurus  upon  the  brain  and, 
in  part  also,  to  direct  irritation  from  the  booklets  of  the  partly  evag- 
inated  larval  tapeworm  heads.  It  is  only  at  this  stage  that  the  turning 
movements  appear,  therefore  the  disease  does  not  truly  merit  the  name 
of  gid  or  turnsickness  until  these  manifestations  are  reached. 

In  gid  of  the  spinal  cord  the  parasite  is  usually  located  in  the  lumbar 
region.  The  chief  symptom  is  a  gradually  increasing  weakness  and 
paralysis  of  the  hind  quarters  (hydatic  paraplegia).  The  bladder  and 
rectum  become  involved  and  the  animal  becomes  progressively  weaker 
and  emaciated.  Death  occurs  in  general  debility  and  exhaustion  after 
a  course  of  one  to  three  months. 

The  s^anptoms  of  gid  in  other  animals  are  of  the  same  general  char- 
acter as  those  in  sheep. 

Control. — Reviewing  the  knowledge  possessed  as  to  the  etiology  of 
gid,  the  measures  to  be  followed  for  its  eradication  are  suggested. 
Chance  infection  of  dogs  by  the  tapeworm  should  be  removed  by  burn- 
ing the  heads  harboring  the  cj'sts,  or  by  cooking  the  affected  brains  if 
they  are  to  be  fed  to  these  animals.  Dogs  kept  in  the  vicinity  of  animals 
susceptible  to  gid  should  be  given  tseniafuge  treatment  every  three 
months  (p.  186).  During  the  operation  of  this  treatment  they  should 
be  confined  and  the  expelled  worms,  fragments,  and  feces  collected  and 
burned  or  deeply  buried. 

Gid  is  a  further  contribution  to  the  accumulating  reasons  why  un- 
cared  for  and  unnecessarj'  dogs — numerically  limitless  in  most  connnu- 
nities — should  be  destroyed. 

Treatment. — On  account  of  the  inaccessible  location  of  the  parasites, 
treatment,  except  by  surgical  means,  is  useless.  The  operative  measure 
consists  in  trephining  the  cranial  cavity  and  removing  the  coenurus, 
but  this  can  only  be  advised  as  practical  in  the  case  of  animals  having 


210  PARASITES  OF  THE  DOMESTIC  ANIMALS 

an  especial  value.  Cold  packs  upon  the  head  or  continuous  irrigation, 
accompanied  by  purgatives,  have  been  recommended  for  the  acute 
stage,  but  such  treatment  can  be  no  moi'e  than  palliative,  and  is  scarcely 
practical  unless  under  exceptional  conditions. 

In  general,  it  is  better,  from  considerations  of  economy,  to  slaughter 
animals  upon  the  first  evidence  of  gid. 

Echinococcosis 

Hydatid  Disease. 

Hydatid  disease  is  caused  by  the  presence  of  Echinococcus  granulosus 
{E.  polymorphus,  E.  multilocularis,  etc.)  or  so-called  hydatid,  the  cystic 
stage  of  the  tapeworm  of  the  dog, — Echinococcus  granulosus  (Tcenia 
echinococcus),  elsewhere  referred  to  under  the  cestodes  of  that  animal 
(p.  181).  It  occurs  in  man  and  all  of  the  domestic  mammals,  the  hy-" 
datids  usually  located  in  the  organs  of  the  abdominal  or  thoracic  cavit}', 
most  often  the  liver,  though  not  infrequently  the  lungs,  spleen,  serous 
membranes,  and  other  organs,  several  of  which  may  be  affected  in  the 
same  animal.  The  disease  is  as  cosmopolitan  as  dogs  and  their  par- 
asites, therefore  it  is  of  world-wide  prevalence. 

The  Echinococcus  (Fig.  117). — While  the  echinococcus  is  the  largest 
of  the  tapeworm  cysts,  the  dog  tapeworm,  of  which  it  is  the  larval  form, 
is  but  5  mm.  (3/16  of  an  inch),  or  thereabouts,  in  length,  and  consists 
of  a  head  and  three  segments.  When  uninfluenced  by  pressure,  the 
echinococcus  cyst  is  more  or  less  spherical  in  shape  and  presents  a  com- 
plex structure,  the  parts  of  which  may  be  set  forth  for  study  as  follows: 

1.  An  external  cuticular  membrane  (hydatic  membrane). 

2.  An  internal  germinal  membrane. 

3.  The  fluid  which  distends  the  vesicle. 

4.  The  proligerous  vesicles,  which  contain  the  larval  tapeworm  heads. 

5.  The  daughter  vesicles. 

Surrounding  the  whole  is  a  capsule  formed  from  the  connective 
tissue  of  the  organ  in  which  the  structure  is  lodged. 

1.  The  cuticular  membrane  limits  the  echinococcus  externally.  It 
is  whitish  in  color,  concentrically  laminated  in  structure,  and  in  large 
vesicles  may  attain  a  thickness  of  1  mm. 

2.  The  germinal  membrane  is  much  thinner  than  the  cuticular, 
usually  not  exceeding  20-25  microns  in  thickness.  On  its  internal  sur- 
face there  appear  groups  of  small  papilke,  representing  the  beginning 
development  of  the  proligerous  vesicles. 

3.  The  hydatic  fluid  is  colorless  or  yellowish  and  in  reaction  is  neutral 
or  slightly  acid.  It  may  contain  a  number  of  substances,  mostly  de- 
rived by  endosmosis  from  the  blood  and  lymph  of  the  organ  invaded. 

4.  The  proligerous  vesicles  appear  on  the  internal  surface  of  the 


THE  TAPEW0R:M  LARV.E 


211 


germinal  membrane  when  the  mother  vesicle  has  developed  to  a  suffi- 
cient size.  At  first  papillary,  each  has  a  cavity  that  gradually  enlarges, 
and  the  vesicles  thus  formed  have  an  attachment  to  the  germinal  mem- 
brane by  a  short  pedicle.  Within  each  there  develops  a  variable  num- 
ber— usuallv  five  to  twentv  or  moi-e — of  little  oval  bodies.     These  are 


Fig.  117. — Diagram  of  EchiuDcocus  liydatid:  cu,  thick  cuticu- 
lar  monibrane;  gr,  germinal  ni("iiil)raiic;  a.  b.,  development  of 
proligerous  vesicle;  c,  development  of  the  heads  according  to 
Leuckart;  d,  development  of  heads  according  to  Moniez;  e,  fully 
developed  brood  capsule  with  heads;  f,  brood  capsule  has  ruptured 
and  the  heads  hang  into  the  lumen  of  the  hydatid;  g,  liberated 
head  floating  in  the  hydatid;  h,  i,  k,  1,  m,  formation  of  secondary 
exogenous  daughter  cyst;  n,  o,  p,  formation  of  endogenous  cyst, 
after  Kuhn  and  Davaine;  cj,  daughter  cyst  with  one  endogenous 
and  one  exogenous  grand-daughter  cyst;  r.  s.,  formation  of  en- 
dogenous daughter  cysts,  after  Xaunyn  and  Leuckart;  r,  at  ex- 
pense of  head;  s,  from  brood  capsule;  t,  constricted  portion  of  the 
mother  cyst  (copied  from  Osborn's  "Economic  Zoology,"  after 
R.  Blanchard;  Bureau  An.  Ind.,  U.  S.  Dept.  Agr.) 

the  lar\'al  tapeworm  heads.  When  completely  formed  the  heads  meas- 
ure slightly  more  than  0.1  mm.  and  show  the  suckers  and  double  crown 
of  hooks. 

5.  Daughter  or  secondary  vesicles  sunilar  in  character  to  the  mother 
vesicle  have  origin  in  the  hydatic  membrane  which  they  distend  and 
finally  rupture,  faUing  into  or  outside  of  the  mother  vesicle.  In  the 
first  case  they  are  termed  endogenous  vesicles.,  in  the  second  exogenous 


212  PARASITES  OF  THE  DOMESTIC  ANIMALS 

vesicles.  The  exogenous  vesicles  are  capable  of  implantation  upon 
organs  somewhat  remote  from  the  primary  vesicle.  This  occurs  more 
commonly  in  the  pig  and  ruminants  than  in  man. 

The  daughter  vesicles  may,  in  the  same  manner,  give  off  grand- 
daughter vesicles  which,  like  the  parent  vesicles,  maj^  be  endogenous 
or  exogenous. 

All  of  these  vesicles  develop  proligerous  vesicles  and  consequently 
the  larval  tapeworm  heads,  or  they  may  remain  sterile,  in  which  case 
they  are  referred  to  as  acejjhalocysts. 

It  will  be  noted  from  the  foregoing  that  one  onchosphere  ma}^  develop 
hundreds  of  tapeworm  heads. 

The  echinococcus  is  usually  considered  as  one  species,  though  there 
is  a  form  which  has  received  the  name  of  Echinococcus  multilocularis 
{E.  alveolaris),  thought  to  be  due  to  a  tapeworm  -.hffering  slightly  from 
E.  granulosus.  Its  main  distinguishing  character  is  the  size  of  the 
vesicles,  which  does  not  exceed  that  of  the  pea.  They  have  a  honey- 
comb arrangement,  and  are  filled  with  a  gelatinous  material,  the  majority 
of  the  cysts  remaining  sterile.  The  mass  of  vesicles  may  grow  to  the 
size  of  a  child's  head,  and  constitutes  a  verj^  fatal  form  of  echinococcosis. 
It  has  been  found  in  the  ox  and  pig,  but  more  frequently  in  man. 

Development. — Embryos  finding  their  way  to  the  intestine  with 
food  or  water  that  has  been  contaminated  Avith  egg-containing  excrement 
of  dogs  are  probably  carried  to  the  liver  by  the  portal  system.  Four 
weeks  after  infecting  pigs,  Leuckart  found  small  white  nodules  about 
1  mm.  in  diameter,  each  with  a  capsule  derived  from  the  hepatic  con- 
nective tissue,  and  containing  within  it  the  globular  echinococcus.  At 
about  five  months  the  cysts  were  the  size  of  a  hazelnut,  and  each  con- 
tained a  thick-walled  whitish-colored  vesicle, — the  mother  vesicle. 

The  development  of  the  echinococcus  is  slow.  It  may  remain  simple 
and  its  growth  be  limited  to  increase  in  volume  and  thickening  of  the 
cuticular  membrane,  in  which  case  it  may  reach  a  diameter  of  15  cm. 
(6  inches) .  Generally  its  size  does  not  exceed  that  of  an  orange,  and  its 
growth  is  attained  by  the  formation  of  secondary  vesicles.  Where  these 
pass  to  the  inside  of  the  mother  vesicle  this  becomes  dilated  in  an  irreg- 
ular manner,  influenced  somewhat  by  the  compression  of  the  adjacent 
organs  of  the  host  (Fig.  117). 

As  regards  the  formation  of  the  daughter  vesicles,  the  process  has 
usualh^  been  described  as  a  normal  one  following  the  complete  develop- 
ment of  the  hydatid.  Deve,  in  a  paper  upon  this  subject  (1917),  states 
that  every  multivesicular  cyst  is  one  which  has  had  its  vitahty  menaced, 
and  that  the  endogenous  vesicles  are  the  result  of  a  defense  reaction. 
The  simple  cyst  with  its  brood  capsules,  according  to  this  authority, 
represents  the  normal  Iwdatid. 


THE  TAPEWORM  LARV.E  213 

Tabular  Review  of  Life  History  of  Echinococcus  Granulosus 
Adult  Tapeworm. — In  intestine  of  clog. 

Egg. — Expelled  from  intestines. 

I 
Embryo . — Released  from  egg  in  digestive  tract  after 
I  ingestion   by   pig,   ruminant,    or   other 

1  mammal. 

Mother  Vesicle  (Hydatid).— In   liver  or  other  organ   of 
I  I  same. 

Daughter  Vessicles 

Scoleces. — ^Attached  to  intestinal  wall  of  dog 
i        after  ingestion  of  brood  capsules  con- 
1        taining  larval  heads. 
Adult  Tapeworms. — In  intestine  of  dog. 

Regarding  the  longevity  of  the  hydatids,  such  information  as  is  pos- 
sessed is  furnished  mainly  by  cases  of  hydatid  disease  occurring  in  man. 
A  case  is  recorded  of  the  persistence  of  an  echinococcus  cj^st  in  a  horse 
for  seven  years.  Usually  when  found  in  lower  animals  it  is  in  those 
slaughtered  for  food,  and  in  most  such  cases  the  animals  are  not  old 
enough  for  the  hj^datids  to  have  reached  their  full  development.  It  is 
probably  for  this  reason  that  the  disease  is  clinically  unobserved  or  is 
much  less  serious  in  these  animals  than  in  man  where  the  hydatid  devel- 
opment remains  uninterrupted. 

The  hmnan  evidence  seems  to  indicate  that  the  longevity  of  the  cyst 
may  be  only  limited  by  that  of  its  host,  for  a  case  is  recorded  where  it 
had  existed  for  thirty-five  years  and  another  where  the  swelling  had 
gradually  spread  over  the  face  for  fortj^-three  years,  and  when  operated 
upon  had  attained  the  size  of  a  child's  head. 

Post-mortem  Appearance. — Hepatic  echinococcosis  is  accompanied 
by  considerable  alteration.  When  the  cyst  is  large  the  liver  becomes 
hj^pertrophied  and  its  weight  may  be  increased  as  much  as  ten  times 
that  of  normal.  The  increase  in  volume  may  compress  neighboring 
organs,  hindering  their  function  and  displacing  them.  The  diaphragm 
especially  is  crowded  and  pressed  forward  upon  the  lungs.  The  surface 
of  the  liver  has  protruding  elevations  of  various  size  and  number,  and 
Glisson's  capsule  is  noticeably  thickened,  perhaps  forming  adhesions 
with  contiguous  organs.  Section  of  the  organ  reveals  cavities  of  un- 
equal size  from  which  the  hydatic  liquid  with  contained  vesicles  flows 
out.  The  connective  tissue  capsules  of  the  cysts  will  vary  in  thickness 
from  3  to  10  mm.  (1/16  to  3/8  of  an  inch).  These  capsules  are  structurally 


!14 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


somewhat  compact,  and  are  generally  little  adherent  to  the  wall  of  the 
hj'-datid. 

Old  liA'datids  may  become  considerabty  modified  or  completely 
destro3'ed.  In  such  cases  the  walls  are  much  thickened  and  show 
degenerative  changes.  The  fluid  diminishes  and  disappears  with  the 
contraction  of  the  cavity,  the  degenerative  material  in  the  walls  be- 
comes more  dense,  there  is  calcareous  infiltration,  and,  finally,  the 
h3'datid  may  be  transformed  into  a  calcareous  mass. 

Symptoms. — The  symptoms  of  hepatic  echinococcosis  in  lower 
animals  are,  as  a  rule,  too  vague  for  recognition  of  the  specific  affection; 


Fig.  118. — Echinococcus  granulosus,  with  fibrous  sac  laid  )Dacl<,  showing 
with  brood  capsules  (after  Leuckart). 


,-datid 


it  usually  remains  for  post-mortem  examination  to  establish  the  diagno- 
sis. Pulmonary  echinococcosis  is  generally  accompanied  by  the  hepatic 
form,  and  may  exhibit  respiratory  disturbances,  as  accelerated  respira- 
tion and  dyspnoea, — sjanptoms  which  may  be  contributed  to  by  pressure 
•of  the  enlarged  liver  upon  the  diaphragm.  In  the  region  invaded  by  tlie 
hydatid  the  vesicular  murmur  is  lessened  or  wanting,  while  in  parts 
nearby  it  is  increased.  Percussion  will  generally  definitely  establish 
its  location. 

Hydatid  disease  rarely  progresses  to  a  fatal  termination  in  lower 
animals. 

Control. — As  the  tapeworm  from  which  the  echinococcus  is  derived 


THE  TAPEWORM  LAR\  .E  215 

is  harbored  by  the  dog,  rarely  the  cat,  infection  of  man  and  domestic 
animals  is  by  the  dissemination  of  the  eggs  of  this  tapeworm  with  the 
excrement  of  its  hosts.  It  follows  that  all  hydatic  viscera  in  slaughter- 
ing establishments  or  elsewhere  should  at  once  be  destroyed  bv  burning, 
thus  preventing  the  larval  tapeworm  heads  from  reaching  the  intestines 
of  dogs  and  cats.  Where  the  disease  has  appeared  it  is  a  good  precau- 
tionary measure,  though  often  impractical,  to  administer  tceniafuge 
treatment  (p.  186)  at  repeated  intervals  to  all  dogs  in  the  vicinity. 
During  the  treatment  the  animals  should  be  confinetl  where  their  feca! 
material  can  be  caiefully  collected  and  burned. 


CHAPTER  XVIII 

PHYLU:\I  III.  CCELHELISIIXTHES 

The  Smooth  and  Segmented  Roundworms 

The  Ccelhelniinthes  are  distinguished  from  all  of  the  worms  thus  far 
considered  by  the  presence  of  a  coelom,  or  bodj'  cavity  located  between 
the  outer  body  wall  and  the  intestine.  With  the  exception  of  the  thorn- 
headed  worms,  the  digestive  tract  is  complete,  and  there  may  or  may 
not  be  a  closed  blood  circulation.  Excretory  vessels  connect  the  cavity 
of  the  bodj^  with  the  outside.  The  body  muscles  are  ''epithelial  muscle 
cells"  developed  from  the  outer  epithelial  wall  of  the  coelom.  Sub- 
groups exhibit  distinct  differences  in  the  character  of  the  coelom.  In 
the  Annelida,  to  Avhich  the  earthworms  belong,  it  is  segmented,  the 
segments  (somites)  corresponding  to  the  annulations  or  ringing  of  the 
body  wall.  In  the  Nemathehninthes,  which  includes  most  of  the  par- 
asitic species,  there  is  no  segmentation  of  the  body  cavity  or  annulation 
of  the  body  wall.  In  the  Hirudinea,  the  annulated  group  which  con- 
tains the  leeches,  the  coelom  is  but  shghtly  developed,  and  usually  the 
annulations  outnumber  the  somites. 

The  phylum  Coelhelminthes  has  the  two  classes  named  below  for 
discussion  in  this  work,  the  first  containing  all  of  the  endoparasitic 
worms  which  remain  to  be  considered,  while  of  the  second,  only  the 
leeches  are  of  direct  parasitic  interest. 

Class  I.  Nemathehninthes. — Body  without  external  or  internal  seg- 
mentation. 

Class  II.  Annelida. — Body  with"  external  and  internal  segmentation. 

Class  I.  Nemathelminthes 

Coelhelminthes  (p.  216). — This  group  contains  the  roundworms,  or 
so-called  threadworms,  though  not  all  are  filiform.  There  are  both 
free  and  parasitic  forms,  examples  of  the  former  living  under  stones 
and  in  other  moist  places.  The  parasitic  species  are  by  far  the  more 
numerous  and  important. 

The  bod}^  is  elongated,  and,  in  being  cylindrical,  differs  from  that  of 
the  Platyhelminthes  which  is  flat,  while  the  absence  of  annulations  and 
segmentation  distinguishes  it  from  that  of  the  Annelida. 

The  class  includes  two  parasitic  orders.    The  first  contains  the  typical 


CCELHELMINTHES 


217 


representatives  of  the  class  and,  with  the  exception  of  the  thorn-headed 
worms,  all  of  the  species  of  medical  interest. 

Order  I.  Nematoda. — Alimentary  canal  present. 

Order  II.  Acanthocephala. — Thorn-headed.  Alimentary  canal  ab- 
sent. 

Order  I.  Nematoda 

Xemathelminthcs  (p.  216). — The  order  Nematoda  includes  numerous 
species  having  a  wide  distribution  as  parasites  of  animals  and  plants. 
The  outer  surface  of  the 
body  is  covered  by  a 
tough  chitinous  cuticle 
which  is  secreted  b}'  an 
underlying  layer  corre- 
sponding to  the  epithe- 
lium and  derma.  The 
cuticular  surface  may  be 
plain,  striated,  or  more  or 
less  mottled.  Transverse 
section  of  the  body  wall 
shows  four  thickenings — 
two  median  and  two 
lateral — corresponding  to 
the  dorsal,  ventral,  and 
lateral  lines  which  are 
cUsposed  longitudinally. 
Within  the  lateral  thick- 
enings are  contained  the 
two  excretory  vessels 
which,  in  the  vicinity  of 
the  head,  unite  by  a 
transverse  commissure 
reaching  the  exterior  on 
the  ventral  surface.  The 
muscles  are  a  layer  of 
vesicular     cells     derived 

from  the  epithelium  of  the  outer  coelomic  wall.  They  are  divided  by 
the  lateral  and  median  lines  into  four  fields,  and  so  project  into  the 
coelom  as  to  occupy  considerable  of  its  space  (Fig.  119). 

The  digestive  system  is  simple  and  complete,  beginning  with  the 
anterior  terminal  mouth  and  ending  in  an  anus  which  is  ventral  and 
close  to  the  caudal  extremity  of  the  body,  A  muscular  esophagus  suc- 
ceeds the  mouth,  soon  expanding  to  form  a  bulbous  sucking  organ 
lined    throughout    with  a  cuticular  layer.     From   this  point  to 


Fig.  119. — Transection  of  t)ody  of  Ascaris  equi  (fe- 
male), showing  cuticular  wall,  muscle  cells  and  proto- 
plasmic processes  extending  into  ccclom,  transversely 
cut  portions  of  ovary  and  uterus,  and  intestinal  canal  in 
center  (from  microphotograph  by  Hoedt). 


the 


218 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


anus  the  alimentary  canal  is  usually  a  uniform  tube  with  little   or 
no  flexion. 

The  nervous  system  consists  of  a  nerve  ring  surrounding  the  esophagus, 
and  of  the  nerves  given  off  from  this  ring  passing  forward  and  back, 
the  largest  of  which  are  in  the  dorsal  and  ventral  lines.  Along  the  course 
of  these  nerves  there  are  ganglionic  cells,  but  there  is  no  massing  to  form 
true  ganglia  as  occurs  in  the  Annelida. 

The  sexes  are  usually  separate,  hermaphroditic  forms  occurring 
among  free-living  species.     In  general,  the  females  attain  a  distinctly 

greater  length  and  thickness  of 
the  body  than  do  the  males,  and 
in  other  respects  they  can  easily 
be  distinguished.  The  males  are 
usually  provided  with  chitinous 
copulatory  organs  known  as 
spicules.  These  are  curved, 
spine-like  structures  which  lie 
in  a  sheath  close  to  the  anus, 
and  they  can  be  protruded  or 
retracted  through  the  cloacal 
opening  (Fig.  120).  They  are 
usually  two  in  number,  but 
there  ma}^  be  but  one.  The 
character  of  the  spicules  often 
serves  as  a  guide  in  the  estab- 
lishment of  relationships  of  cer- 
tain groups.  Surrounding  the 
spicules  there  is,  in  some  forms, 
a  membraneous  expansion  which 
is  referred  to  as  the  caudal  bursa 
or  pouch.  This  structure  is  best 
developed  in  the  Strongylidse, 
where  its  varied  characteristics 
furnish  an  aid  in  the  recognition 
of  species.  The  bursa  is  a  clasp- 
ing organ  used  in  copulation,  while-  the  spicules  serve  to  direct  the  course 
of  the  semen.  In  the  female  there  is  a  special  genital  opening,— the 
vulva,  located  on  the  ventral  anterior  half  of  the  body,  or  it  may  be  to- 
ward the  anus,  its  position  varying  according  to  species.  The  cylindrical 
body  is  usually  more  or  less  distended  with  eggs,  and  frequently  the 
egg-packed  uteri  can  be  distinctly  seen  under  low  magnification  and 
transmitted  light. 

The  internal  reproductive  systems  of  the  male  and  female  are  much 
alike.    In  both  they  are  long  tubular  organs,  coiled  forward  and  back. 


Fig.  120. — Posterior  extremity  of  male  nema- 
tode; diagrammatic  longitudinal  section:  cl, 
cloaca;  d,  intestine;  m,  retractor  muscle  of 
spicule;  s,  sheath  of  spicule;  w,  body-wall  (after 
Boas,  by  Kirkaldy  and  Pollard). 


C(ELHELMINTHES  219 

and  lying  loosely  in  the  coelomic  cavity.  In  the  nial(>  this  genital  tract 
is  always  single,  the  finer  part  of  the  tube  constituting  the  testis,  the 
heavier  remaining  portion  serving  as  a  seminal  vesicle  and  terminating 
in  the  duct.  The  ovaries  and  uteri  are  likewise  continuous  structures, 
the  former  being  constituted  by  the  finer  portions,  while  the  uteri  are 
usually  much  distended  (Fig.  119).  In  certain  forms  there  is  but  one 
genital  tube  in  the  female,  but  in  most  all  there  are  two  which  unite 
close  to  the  external  opening  to  form  the  vagina.  There  is  no  distinct 
vitellarium  as  in  the  flatworms,  the  ovary  assuming  the  function  of  this 
gland. 

The  eggs  are  usually  globular  or  ovoid  in  shape;  as  there  is  copulation, 
they  are  fertilized  in  the  uterus.  Following  this  the  development  may 
or  may  not  take  place  while  the  eggs  are  retained. 

As  to  the  terms  oviparous  and  ovoviviparous.  frequentl}'  used  in 
summarizing  the  characteristics  of  parasitic  groups,  it  may  be  well  to 
direct  attention  here  to  their  correct  application. 

The  term  oviparous  is  properly  applied  to  the  oviposition  of  eggs 
which  undergo  incubation  after  they  have  been  oviposited,  or  to  the 
oviposition  of  eggs  which  have  been  incubated  within  the  genital  cavity 
of  the  female  and  at  the  time  they  are  oviposited  contain  enil)ryos  more 
or  less  developed. 

The  word  ovoviviparous  is  commonly  used  hi  reference  to  the  oviposi- 
tion of  eggs  containing  embryos  developed  and  ready  to  emerge  at  the 
time  the  eggs  are  extruded,  as  might  be  in  the  last-stated  case.  It  is 
more  correctly  applied  where  the  embryos,  having  been  developed, 
escape  from  the  eggs  while  these  are  still  within  the  body  of  the  female. 

In  other  words,  the  escape  of  the  embryos  from  the  eggs  occurs  out- 
side of  the  body  of  the  parent  in  the  oviparous  method,  within  the  parent 
body  in  the  ovoviviparous. 

The  term  viviparous,  often  applied  in  biology  for  ovoviviparous, 
has  reference  to  the  typical  mammalian  method  of  giving  birth,  where 
the  egg  is  not  concerned  in  this  process,  and  there  is  consequently  no 
hatching. 

Parasitism  of  the  Nematodes  in  General   . 

In  most  of  the  nematode  parasites  there  is  a  post-embryonic  free 
existence,  the  infection  of  the  host  being  direct  and  necessary  to  the 
parasite's  sexual  maturity.  A  notable  exception  is  furnished  by  Trich- 
inella,  where  there  is  no  period  of  free  life,  the  transfer  from  host  to 
host  being  accomplished  by  the  ingestion  of  food  containing  the  encysted 
larvae. 

The  degree  of  injury  to  their  hosts  by  the  nematodes  varies  consider- 
ably and  is  frequently  not  characteristic.  In  general,  it  may  be  said 
to  depend  upon  the  number  of  the  parasites  present,  but  the  seriousness 


220  PARASITES  OF  THE  DOMESTIC  ANIMALS 

of  their  effect  does  not  depend  upon  this  wholly.  A  relatively  light 
invasion  with  forms  which  elaborate  toxins  possessing  a  high  degree  of 
toxicity  may  have  a  more  deleterious  influence  upon  the  health  of  the 
animal  than  a  heavier  infestation  with  worms  from  which  the  elimina- 
tions are  less  toxic.  Again  independent  of  numbers,  adult  worms  or 
their  larvae  can,  by  their  migrations,  set  up  in  their  unusual  locations 
serious  inflammatory  and  degenerative  changes  which  may  be  of  an 
infective  character  due  to  the  bacteria  which  they  transport. 

Intestinal  worms  which  attach  to  the  mucosa  are  far  more  capable 
of  producing  serious  effects  than  those  which  live  free  in  the  intestinal 
contents.  The  former  live  upon  the  tissues  of  their  host  and  cause  at 
their  attachment  a  wound  through  which  infection  may  readily  enter, 
while  the  latter  obtain  their  nourishment  from  the  partly  digested 
alimentary  material  and  do  not  directly  lacerate  the  mucosa. 

Location  is  a  main  pathogenic  factor.  This  may  be  accidental  by 
active  or  passive  migration,  as  in  the  case  of  adult  or  larval  filarise, 
which  seem  capable  of  wandering  to  most  any  part  of  the  body,  or  it 
may  be  specific,  certain  nematodes  normally  infesting  only  the  intestines, 
others  the  respiratory  tract,  while  some  occupy  the  blood  vascular 
system  in  their  larval  state  or  both  as  larvae  and  adults.  Again,  Trich- 
inella  spiralis  causes  its  most  serious  disturbance  during  the  migration 
of  the  embryos  through  the  musculature  of  its  host.  In  general,  it  may 
be  said  that  nematode  invasion  of  the  intestines  is  less  serious  than  that 
of  the  respiratory  tract.  The  injurious  effects  from  verminous  parasitism 
of  the  blood  are  usually  due  to  injury  to  the  vascular  walls,  or,  if  the 
worms  are  numerous  and  massed,  to  interference  with  the  blood  flow. 
Following  upon  this  there  may  be  the  production  of  a  thrombus  and 
formation  of  emboli  with  the  subsequent  development  of  aneurism. 
AVhile  parasites  in  the  blood  in  any  case  constitute  a  serious  infection, 
the  greater  number  of  specific  conditions  due  to  such  parasitism  are 
caused  by  blood-invading  Protozoa. 

The  specific  limitations  as  to  host  of  the  parasitic  worms  is  probably 
much  influenced  by  the  character  of  the  nutriment  with  which  they  are 
supplied  in  each  particular  case.  Certain  hosts  having  no  more  than  a 
class  relationship  may  harbor  intestinal  worms  of  the  same  species,  but 
are  more  likely  to  do  so  if  there  is  a  measure  of  similarity  in  the  char- 
acter of  the  hosts'  alimentation.  This  is  exemplified  in  the  distinctly 
omnivorous  animals,  man  and  the  pig,  each  furnishing  hostage  for  the 
intestinal  worms  Ascaris  lumbricoides  (A.  suis)  and  Gigantorhynchus 
hirudinaceus,  while,  again,  the  carnivorous  dog  and  cat  both  harbor 
Belascaris  marginata  and  Anktjlostoma  canina. 

Opportunity  is  also  a  factor.  Animals  of  similar  diet  are  alike  exposed 
to  infection  by  food  specific  for  or  most  likely  to  be  contaminated  with 
larvae  or  eggs  of  certain  species  of  parasites.     Such  parasitism  as  the 


CCELHELMINTHES  221 

invasion  of  the  intestines  of  man  by  the  thorn-headed  worm  of  the  pig 
{Gigantorliynchus  hirudinaceus)  is  regarded  as  straj"  or  accidental,  ])iit 
if  the  grub  of  the  May  beetle,  the  larval  host  of  this  worm,  constituted 
a  choice  morsel  of  diet  for  man  as  it  does  for  the  pig,  it  is  probable  that 
the  thorn-headed  worm  would  much  more  frequently  inhabit  man's 
intestines. 

Adaptive  modifications  from  a  free  to  a  parasitic  life,  and  adaptations 
of  the  parasite  to  differing  host  environments,  or  to  new  locations  taken 
up  in  the  body  of  the  same  host,  are  best  exemplified  in  the  Protozoa. 
In  the  more  complexly  organized  wo^ns  the  faculty  of  adaptation  is 
possessed  in  less  degree;  though  undoubtedl}-  the  parasitic  forms  have 
without  exception  passed  through  at  least  the  first  of  the  gradations 
mentioned.  The  adult  nematodes  infesting  the  respiratory  tract,  as 
Didyocaulus  filaria  of  sheep,  and  those  infesting  the  blood  vascular 
system,  as  Dirofilaria  immitis  of  the  dog,  have  probabl.y  reached  these 
regions  from  a  priniar}'  parasitism  in  a  less  obscure  part  of  the  body, 
the  adaptivitj'  having  become  sufficiently  fixed  that  the  conditions 
supplied  by  the  location  later  acquired  are  now  specifically  essential 
to  their  sexual  development  and  reproduction. 

Treatment  in  General. — Treatment  in  nematode  helminthiasis  has 
in  view  primarily  the  expulsion  of  the  worms,  and  secondarih'  the 
building  up  of  the  general  health  of  the  animal.  Anthelmintics  act  by 
destroying  or  in  some  way  so  affecting  the  worms  that  they  are  easily 
expelled  from  the  body.  An  agent  capable  of  killing  the  parasites  may 
have  a  like  effect  upon  the  host  if  used  without  due  precaution;  in  any 
event  it  is  likel}-  to  be  too  drastic  and  cause  an  acute  disturl)ance  more 
serious  than  the  subacute  one  which  it  is  sought  to  remedy.  In  the 
case  of  intestinal  worms,  remedies  which  reduce  them  to  a  sufficiently 
passive  state  that  they  may  be  readily  swept  out  by  the  action  of  a 
purgative  are  to  be  preferred;  and  here  the  effect  of  the  vermifuge 
upon  the  host,  as  compared  with  that  of  a  true  vermicide,  is  one 
of  degree,  and  the  tolerance  of  the  patient  is  to  be  taken  into  con- 
sideration. 

Essentially  the  success  of  vermifuge  treatment  will  ])e  influence  1  by 
the  location  of  the  worms;  only  those  in  tubular  organs  in  communica- 
tion with  the  outside  can  be  reached  by  such  medication,  while  its  action 
will  be  hampered  in  the  case  of  those  which  burrow  into  and  attach 
upon  the  mucous  lining. 

It  has  been  said  that  it  may  be  taken  as  an  axiom  in  helminthology 
that  each  worm  in  the  body  develops  from  an  egg  or  larva  which  has 
entered  from  without.  Worms  do  not  go  on  multiplying  indefinitely 
with  the  production  of  new  adult  generations  in  the  same  host.  The 
degree  of  the  infestation,  therefore,  depends  primarily  upon  the  degree 
of  contamination  of  food  or  water  taken  in  by  the  animal,  and  secondarily 


2^12  PARASITES  OF  THE  DOMESTIC  ANIMALS 

upon  the  susceptibility  and  favorable  hostage  offered  by  the  individual 
to  the  parasite. 

It  follows  that  preventive  measures  should  be  based  upon  the  life 
history  of  the  species  to  which  such  measures  are  applied.  Where 
this  is  known  and  intelligently  taken  advantage  of,  the  problem  of  the 
eradication  of  the  parasites  becomes  much  easier  of  solution  than  it 
otherwise  would  be.  For  the  same  reason,  more  detailed  reference  to 
control  is  reserved  for  application  to  particular  cases  in  the  pages  to 
follow. 

The  nematode  parasites  are  to  be  considered  under  seven  families 
having  marked  differences  as  to  parasitic  habit  and  also  as  to  degree 
of  injury  which  they  cause  in  their  hosts.    These  are  as  follows: 

Family      I.  Ascaridae. 

Family     II.  Oxjau'idae. 

Family  III.  Heterakidse. 

Family   IV.  Filariidse. 

Family     V.  Strongjdida?. 

Family   VI.  Eustrongylidae. 

Family  VII.  Trichinellidse. 

Classification  of  Parasites  of  the  Phylum  Ccelhelminthes 

Phylum  III.  Coelhehninthes.    P.  216. 

Class  A.  Nemathelminthes.    Smooth-bodied  roundworms.    P.  216. 
Order  1.  Nematoda.    P.  217. 
Family  (a)  Ascaridae.    P.  229. 
Genus  and  Species: 

Ascaris  equi.    Host,  equines.    P.  233. 
Belascaris  marginata.    Host,  dog,  cat.    P.  237. 
Toxascaris  limbata.    Host,  dog.    P.  238. 
Ascaris  lumbricoides.    Hosts,  man,  hog,  sheep.    P.  239. 
A.  vitulorum.    Host,  cattle.    P.  241. 
Family  (b)  Oxjairidse.    Seat  worms.    P.  235. 
Genus  and  Species: 

Oxyuris  equi.    Host,  equines.    P.  235. 
Family  (c)  Heterakid^.    P.  242. 
Genus  and  Species: 

Heterakis  perspicillum.    Host,  poultry.    P.  242. 
H.  vesicularis.    Host,  poultry.    P.  242. 
Family  (d)  Filariidge.    P.  244. 
Genus  and  Species: 

Set  aria  labiato-papillosa.  Host,  equines.  P.  244. 
Habronema  megastoma.  Host,  equines.  P.  245. 
H.  microstoma.    Host,  equines.    P.  246. 


CCELHELMIXTHES  223 

Gon^ylonema  scutata.    Hosts,  sheep,  cattle.    P.  247. 

Filaria  labiato-papillosa.    Hosts,  cattle,  deer.    P.  248. 

Dirofilaria  iinmitis.    Host,  dog.    P.  248. 

Spiroptera  sangiiinolenta.    Host,  dog.    P.  250. 

Ardiienna  strongylina.    Host,  hog.    P.  251. 

Physocephahis  sexalatiis.    Host,  hog.    P.  252. 

Dispharagus  spiralis.    Host,  poiiltiy.    P.  254. 

D.  hamulosiis.    Host,  poultry.    P.  254. 

D.  nasiitus.    Host,  poultiy.    P.  254. 

Tetrameres  fissispina.    Host,  poultry.    P.  254. 
Family  (e)  Strongylida.    P.  255. 
Genus  and  Species: 

Stephanurus  dentatus.    Host,  hog.    P.  295. 
Subfamily  (a)  Metastrongylins    AVoi-ms  of  the  respiratory  tract. 
P.  256. 
Genus  and  Species: 

Dictj'ocaulus  filaria.    Hosts,  sheep,  goat.    P.  256. 

Synthetocaulus  rufescens.    Hosts,  sheep,  goat.    P.  257. 

S.  capillaris.    Hosts,  sheep,  goat.    P.  258. 

Dictyocaulus  yiviparous.    Host,  cattle.    P.  259. 

jMetastrongylus  apri.    Host,  pig.    P.  260. 

M.  breyiyaginatus.    Host,  pig.    P.  260. 

Dictyocaulus  arnfieldi.    Host,  equines.    P.  261. 

Htemostrongylus  yasorum.    Host,  dog.    P.  261. 

Synthetocaulus  abstrusus.    Host,  cat.    ?.  262. 
Subfamily  (6)  Trichostrongylina.     Woi-ms  of  the  stomach  and 
intestine.    P.  268. 
Genus  and  Species: 

Hiemonchus  contortus.    Hosts,  sheep,  goat,  cattle.    P.  268. 

Cooperia  cui'ticei.    Hosts,  sheep,  goat.    P.  268. 

Ostertagia  nuu-shalli.    Host,  sheep.    P.  269. 

Trichostrongylus  Lnstabilis.    Hosts,  sheep,  goat.     P.  271. 

Ostertagia  ostertagi.    Host,  cattle.    P.  272. 

Nematodirus  filicollis.    Hosts,  cattle,  sheep,  goat.    P.  273. 

Cooperia  oncoi;)hora.    Hosts,  cattle,  sheep.    P.  275. 
Subfamily  (c)  Strongylinae.     Worms  of  the  large  and  small  in- 
testines.   P.  280. 
Genus  and  Species : 

Q^sophago.stomum  columbianum.     Hosts,  .sheep,  goat.     P. 
281. 

O^.  yenulosum.    Hosts,  sheep,  goat.    P.  282. 

(E.  radiatum.    Ho.st,  cattle.    P.  285. 

(E.  subulatum.    Host,  hog.    P.  287. 

Chabertia  oyina.    Host,  sheep.    P.  287. 


224  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Strong3'lus  equinus.    Host,  equines.    P.  288. 
St.  edentatus.    Host,  equines.    P.  289. 
St.  vulgaris.    Host,  equines.    P.  289. 
Cylicostomuni  tetracanthum.    Host,  equines.    P.  289. 
Ankvlostoma  canina.    Hosts,  dog,  cat.    P.  291. 
Uncinaria  stenocephala.    Host,  dog.    P.  292. 
Bunostomum  trigonocephalum.    Host,  ruminants.    P.  293. 
B.  phlebotomum.    Host,  cattle.    P.  293. 
S3aigamus  trachealis.    Host,  fowl.    P.  293. 
Sj-n.  bronchialis.    Host,  water  fowl.    P.  293. 
Family  (f)  Eustrongylida?.    P.  296. 
Genus  and  Species : 

Dioctoph\ane  renale.    Hosts,  dog  and  other  animals.    P.  296. 
Family  (g)  Trichinellidffi.    P.  299. 
Genus  and  Species: 

Trichuris  ovis.    Host,  ruminants.    P.  299. 
T.  crenatus.    Host,  hog.    P.  299. 
T.  depressiusculus.    Host,  dog.    P.  300. 
Trichinella   spiralis.     Hosts,   hog,   rat,   mouse,   and   other 
mammals.    P.  301. 
Order  2.  Acanthocephala.    P.  306. 

Family  (a)  Gigantorhynchidae.    P.  306. 
Genus  and  Species : 

Gigantorhynchus  hirudinaceus.    Host,  hog,  man.    P.  306. 
Class  B.  Annelida.    Annulated  worms.    P.  307. 
Order  1.  Hirudinea.    Leeches.    P.  307. 
Family  (a)  Gnathobdellidse.    P.  308. 
Genus  and  Species : 
Hirudo  medicinalis.    Medicinal  leech.    P.  309. 
Hsemopis  sanguisuga.    Horse  leech.    P.  308. 

With  slight  omissions,  the  following  descriptions  of  superfamilies 
and  their  subdivisions  are  transcribed  from  a  work  upon  the  nematode 
parasites  of  small  mammals  by  Maurice  C.  Hall  (1916). 

''Esophagus  consists  of  a  chitinous  tube  which  is  embedded  along 
the  greater  part  of  its  length  in  a  chain  of  single  cells.  The  anterior 
portion  of  the  body,  occupied  by  the  esophagus,  usually  very  slender; 
the  posterior  portion,  occupied  by  the  intestine  and  reproductive 
organs,  more  or  less  swollen,  or  at  least  thicker  than  the  anterior  portion. 
Anus  terminal  or  subterminal.  Male  with  only  one  spicule  or  with  no 
spicule.  One  testis.  Female  with  one  ovary.  Vulva  situated  at  the 
junction  of  the  anterior  and  posterior  portion  of  the  body.  Oviparous 
or  ovoviviparous.  In  digestive  tract  or  adnexa  or  in  urinary  bladder 
as  adults.    Life  history  usually  simple.    Larva  of  at  least  one  intestinal 


CCELHELMINTHES  2^25 

form  penetrates  to  and  enc>'sts  in  the  musculature  of  the  host  of  the 
adult  worm. 

Superfamily  Trichmelloidea  Hall,  19 IG. 

Type-family  Trichinellidae  Stiles  and  Crane,  1910. 

"Male  without  spicule.    Female  ovoviviparous;  the  spherical  egg  is 

suri-ounded  with  a  delicate  membrane  and  is  without  a  true  eggshell. 

Worms  in  the  intestine  of  the  host  animal. 

Subfamily  Trichinelliuie  Ransom,  1911. 
Type-genus  Trichinella  Railliet,  1895. 
"Male  with  one  spicule,  or,  exceptionally,  with  onlj-  a  copulatory 
sheath.  Eggs  lemon-shaped,  the  apertures  at  each  end  closed  with 
opercular  plugs.  Development,  so  far  as  known,  direct  and  without 
intermediate  host.  Egg  development  often  slow.  Eggs  with  thick  shell; 
•do  not  hatch  until  swallowed  by  a  suitable  host. 

Subfamily  Trichurinse,  Ransom,  1911. 
Type-genus  Trichuris,  Roederer,  17G1. 
"Mouth  connnonly  provided  with  two  or  three  prominent  or  incon- 
spicuous lips  which  are  often  supplied  with  papilke,  but  the  mouth 
may  be  of  variable  shape  and  without  lips.  When  three  lips  are  present 
one  is  median  and  dorsal,  the  others  are  submedian  and  are  approximated 
in  the  ventral  line.  Buccal  capsule  is  not  present.  Males  are  provided 
with  one  or  two  spicules,  rarel}'  with  none.  Female  with  two  ovaries, 
oviparous,  rarely,  as  in  Oxyuris  vivipara,  viviparous.  As  a  rule  develojj- 
ment  is  direct  and  without  intermediate  host;  exceptionall}'  (as  in 
ascarids  of  fish)  there  is  an  intermediate  host. 

Superfamily  Ascaroidea,  Railliet  and  Henry,  1915. 
"Mouth  with  three  prominent  lips  supplied  with  joapillffi,  the  dorsal 
lip  being  median  and  the  two  other  submedian  and  approximated  in 
the  ventral  line,  or  with  three  main  lips  and  three  relativeh'  prominent 
and  inconspicuous  intermediate  lips  (interlabia).  Male  usually  with 
two  spicules.  Caudal  extremity  of  female  terminates  conically  and 
fairly  abruptly. 

Type-family  Ascaridse,  Cobbold,  1864. 
Type-genus  Ascaris,  Linnaeus,  1758. 
"Mouth  provided  with  two  or  three  lips  or  without  lips  and  of  va- 
riable shape.  Esophagus  cylindrical  or  club-shaped,  often  followed  by 
a  distinct  bulb.  Males  with  a  preanal  sucker,  which  may  be  limited 
by  a  chitinous  ring  or  a  delicate  cutaneous  membrane,  or  formed  by  a 
simple  longitudinal  depression;  this  sucker  is  not  present  in  Seuratum. 
Two  spicules,  one  or  l)oth  of  which  may  tend  to  atrophy  or  show  im- 
perfect chitinization,  and  with  accessory  piece  present  or  absent.  'S'ulva 
near  middle  of  body. 

Family  Heterakidip,  Railliet  and  Henrj',  1914. 
"Mouth  with  three  well-defined  lips;  esophageal  bulb  present  or 


226  PARASITES  OF  THE  DOMESTIC  ANIMALS 

absent;  preanal  sucker  neaiij^  circular  and  limited  by  a  chitinous  ring; 
spicules  equal  or  unequal. 

Subfamily  Heterakinse,  Railliet  and  Henry,  1912. 

Type-genus  Heterakis,  Dujardin,  1845. 

"Mouth  with  simple,  usually  inconspicuous  Hps.    Male  usually  with 

one  spicule,  at  times  reduced,  imperfectly  chitinized  or  absent.    Caudal 

extremity  of  female  much  elongated  and  sublobate.     Vulva  anterior. 

Eggs  characteristically  flattened  on  one  side. 

Family  Ox;ynaridse,  Cobbold,  1864. 

Subfamily  Oxjiirinse,  Hall,  1916. 

Type-genus  Ox^auis,  Rudolphi,  1803. 

''Males  with  a  well-developed  caudal  bursa  supported  by  rays;  in 

forms  near  the  outer  limit  of  the  superfamily  the  bursa  is  occasionally 

verj^  small  and  the  rays  atj^pical,  or  the  bursa  may  be  lacking  altogether. 

Esophagus  without  posterior  bulb.     Mouth  naked  or  with  a  buccal 

capsule  and  six  papillae,  distinct  or  indistinct.    Male  usually  with  two 

spicules  and  female  usually  with  two  ovaries.    Oviparous  or  viviparous. 

Superfamily  Strongyloidea,  Weinlancl,  1858. 

"Buccal  capsule  present.     Bursa  highly  developed,  with  a  typical 

system  of  supporting  rays  consisting  of  one  or  two  dorsal  raj'S  and  two 

lateral  ray  systems  of  six  rays  each.    Male  with  two  spicules  and  female 

with  two  ovaries.    Vulva  at  times  anterior  to  the  middle  of  the  body, 

but  usually  posterior  of  the  middle.    Oviparous,  eggs  segmenting  when 

laid.     Development,  so  far  as  known,  direct.     Embryo  rhabditiform. 

In  digestive,  rarely  in  respiratory  system. 

Type-family  Strongylidae,  Cobbold,  1864. 

"Buccal  capsule  present.     In  digestive,  occasionally  in  respiratory, 

system.     Development  direct,  at  tunes  complex,  involving  cutaneous 

infection,  nodular  development  or  other  embryonic  or  larval  migration. 

Subfamily  Strongylinae,  Railliet,  1893. 
Type-genus  Strongylus,  Mueller,  1780. 
"Simple  mouth  without  a  buccal  capsule.    Parasitic  only  in  the  di- 
gestive system.    Development  direct  and  simple,  involving  in  all  cases 
known  only  the  possibility  of  infection  by  ingestion. 

Family  TrichostrongyUda),  Railliet,  1915. 
' '  Body  straight  or  curved,  but  not  regularly  coiled  in  a  spiral .    Females 
with  two  ovaries. 

Subfamily  Trichostrongylinse,  Leiper,  1908. 
Type-genus  Trichostrongylus,  Looss,  1905. 
"Buccal  capsule  present  or  absent.  Bursa  present  or  absent;  when 
present,  frequently  atypical  in  structure  and  number  of  rays.  Ovip- 
arous, with  eggs  in  variable  stages  of  segmentation  when  oviposited, 
or  viviparous.  Embrj'o  not  rhabditiform.  Usually  in  respiratory  and 
circulator}'  S3^stems,  rarely  in  digestive  sj-stem. 


COELHELMINTHES  227 

Family  ]\Ietastrongylidse,  Leiper,  1908. 
''Buccal  capsule  absent.     ]Male  with  two  equal  spicules  and  female 
with  two  ovaries.    Eggs  in  van-ing  stages  of  development  when  ovipos- 
ited.   Embiyo  not  rhabditiform.    Parasitic  in  the  respiratory  and  cir- 
culator}'  systems. 

Subfamih'  Metastrongj-linte,  Leiper,  1908. 
T3'pe-genus  Metastrongylus,  Molin,  1861. 
"Body  usually  very  long  and  slender.  Mouth  with  two  lips  or  with- 
out lips  and  surrounded  with  circumoral  papilla?.  Esophagus  slender, 
without  posterior  bulb.  Anus  subterminal.  INIale  with  a  single  spicule 
or  with  two  unequal  spicules.  Tail  provided  with  papillae,  usuall}^ 
curved  spirally,  and  with  bursal  alse  present  or  absent.  Female  larger 
than  male.  Vulva  present,  or,  less  often,  absent  in  gravid  females; 
when  present,  usually  anterior  to  the  middle  of  the  body  or  near  the 
middle,  rarely  near  posterior  extremity.  Oviparous,  ovoviviparous, 
or  viviparous.  Development  in  many  cases,  perhaps  in  all,  requires 
an  intermediate  host. 

Superfamily  Filarioidea,  Weinland,  1858. 
''Body  long  and  filiform.     Alouth  without  lips.     Male  with  two 
spicules,  usually  quite  dissimilar.    Vulva  near  the  anterior  extremity  of 
the  body.    Adults  subcutaneous,  in  blood,  or  on  serous  surfaces. 

Tj^pe-family  Filariidse,  Claus,  1885. 
"Vulva   anterior,   near  mouth.     Spicules   quite  dissimilar.     Inter- 
mediate stages,  so  far  as  known,  occur  in  blood-sucking  arthropoda. 

Subfamily  Filariina?,  Stiles,  1907, 

Type-genus  Filaria,  Mueller,  1787, 

"Mouth  with  two  lips;  or  without  lips  in  forms  where  vulva  is  near 

posterior  extremit}'  of  body,     Male  with  posterior  extremity  of  body 

commonly  expanded  and  alate.     Female  with  \'nlva  usually  in  middle 

portion  of  body,  exceptionally  near  posterior  extremit}^ 

Family  Spiruridae,  (Erly,  1885. 
Type-genus  Spirura,  E.  Blanchard,  1849. 
"Bod}'  long  and  filiform.    Anterior  portion  of  bod}'  ornamented  with 
cuticular  bosses.    In  the  median  lines,  immediately  behind  the  mouth, 
are  two  semilunar  depressions  sinmlating  suckers.     The  vulva  is  sit- 
uated a  short  distance  anterior  of  the  anus. 

Subfamily  Gongyloneminse,  Hall,  1916. 
Type-genus  Gongylonema,  Mohn,  1857. 
"Females  with  two  uteri  and  with  \ailva  in  the  middle  portion  of 
the  body,  not  close  to  anterior  or  posterior  extremities.    Pharjmx  with- 
out cuticular  rays  or  spirals. 

Subfamily  Spirurinae,  Railliet,  1915, 

Type-genus  Spirura.  E.  Blanchard,  1849. 

"INIouth  with  two  lips  leading  into  a  pharynx  which  is  strengthened 


228  PARASITES  OF  THE  DOMESTIC  ANIjVIALS 

by  cuticular  ridges  in  the  form  of  rings  or  spirals.  Spicules  unequal, 
the  longer  several  times  the  length  of  the  shorter.  Four  pairs  of  preanal 
papillae.    Eggs  containmg  embiyos  when  oviposited. 

Subfamily  Arduenninse,  Railhet  and  Henry,  1911. 
Type-genus  Arduenna,  Railhet  and  Henry,  1911. 


CHAPTER  XIX  / 

NEMATODA.  FAIMILY  I.  ASCARID.E 

The  Large  Rouxdworms  of  the  Intestine 

Xematoda  (p.  217).  The  nematodes  of  this  family  have  the  body- 
relatively  thick  (Fig.  125).  The  mouth  is  commonly  provided  with 
three  lips  which  may  be  prominent  or  inconspicuous  and  often  bear 
papillse.  When  three  lips  are  present  one  is  dorsal,  the  other  two  sub- 
median,  touching  on  the  ventral  median  hne  (Fig.  121).  The  males 
are  somewhat  smaller  than  the  females  and  usually  have  the  caudal 
extremity  curved  ventrally  in  the  form  of  a  hook.  There  may  be  one 
spicule  or  two.  The  females  have  two  ovaries  and  they  are  oviparous. 
So  far  as  known,  development  in  all  which  are  parasitic  in  warm-blooded 
animals  is  without  intermediate  host  and  infection  is  direct. 

All  of  the  ascarids  live  as  parasites  in  the  intestines  of  their  hosts, 
though  they  may  be  found  in  other  organs  and  in  the  body  cavities 
reached  by  their  migrations.     They  hve  free  in  the  in- 
testinal contents,  obtaining  their  sustenance  by  absorp- 
tion of  the   partly  digested   nutriment   of  their  host 
through  their  smiple  alimentary  tube. 

Investigations  as  to  Life  History. — Investigations 
by  Capt.  F.  H.  Stewart  (F.  H.  Stewart  On  the  Life 
Histor}'  of  Ascaris  lumbricoides,  British  Medical  Jour- 
nal, 1916,  Vol.  2,  No.  2896)  have  brought  results  of 
great  importance  bearing  upon  the  hfe  histoiy  of  Ascaris  Fig.  121.— Dor- 
lumhricoides  and  closely  related  forms.  In  these  experi-  fj  ^xtremity^^of 
ments  Stewart  found  that  if  rats  or  mice  were  fed  ascarid,  showing 
Ascaris  eggs,  the  eggs  hatched  in  the  alimentaiy  tract  superior  median 
and  the  embr3'os  migrated  to  the  hver,  spleen,  and  lungs,  lateral  lips. 
During  these  migrations  they  passed  through  certain 
developmental  changes,  and  man}-  of  them  finally  again  reached  the 
alimentary  tract  b}^  way  of  the  lungs,  trachea,  and  esophagus.  Within 
the  alimentary  tract  they  did  not  continue  their  development  and  were 
soon  expelled  with  the  feces,  so  that  rats  and  mice  surviving  the  pneu- 
monia commonh'  caused  by  the  invasion  of  the  lungs  became  free  of 
the  parasites  as  earh'  as  the  sixteenth  day  after  infection. 

From  these  findings  Stewart  concluded  that  in  infection  with  Ascaris 
lumbricoides  it  is  necessary  in  the  life  cycle  for  the  eggs  to  be  swallowed 
by  rats  or  mice,  and  that  the  embryos  hatching  from  the  eggs  undergo 


230  PARASITES  OF  THE  DOMESTIC  ANIMALS 

certain  migrations  and  changes  of  development,  after  which  they  may 
be  carried  in  the  feces  or  saHva  of  the  rats  or  mice  to  food  or  other 
materials  which  may  be  ingested  by  human  beings  or  pigs,  thus  ulti- 
matelj^  reaching  their  final  host. 

This  conclusion  is  contrary  to  the  opinion  usually  accepted  that 
Ascaris  infects  man  or  the  pig  directly  through  the  ingestion  of  the  eggs 
of  the  parasite.  In  a  preliminary  note  upon  the  life  history  of  Ascaris 
lumhricoides  and  related  forms  Ransom  and  Foster,  of  the  Zoological 
Division  of  the  Bureau  of  Animal  Industry,  state  that  in  a  repetition 
of  Stewart's  experiments  in  feeding  rats  and  mice  with  Ascaris  eggs 
they  obtained  results  agreeing  very  closely  with  those  which  he  had 
recorded,  also  that  further  investigations  have  shown  that  guinea  pigs 
as  well  as  rats  and  mice  may  be  similarly  infected  by  feeding  Ascaris 
eggs.  Their  negative  or  uncertain  results  from  attempts  to  infect  pigs 
with  Ascaris  by  feeding  the  eggs  agreed  with  the  experience  of  Stewart 
and  other  investigators,  nevertheless  they  did  not  feel  justified  in  accept- 
ing these  results  as  evidence  against  the  hypothesis  of  a  direct  develop- 
ment without  an  intermediate  host.  They  note  that  Epstein  in  care- 
fully controlled  experiments  with  feeding  eggs  of  Ascar'is  lumbricoides 
used  very  young  subjects  and  that  the  positive  results  which  he  obtained 
can  scarcel}^  be  explained  upon  any  other  assumption  than  that  a  direct 
development  of  the  parasites  occurred  following  feeding  of  the  eggs. 
The  failures  of  others  to  infect  adult  human  beings  and  the  unsuccessful 
attempts  to  infect  pigs  several  months  old  in  the  same  way  are  considered 
as  suggesting  the  possibility  that  age  is  an  important  factor  influencing 
the  susceptibility  of  human  beings  and  pigs  to  infection  with  Ascaris. 
In  support  of  this,  and  in  agreement  with  the  migration  of  larvse  which 
occurs  in  rats  and  mice,  they  cite  an  instance  of  a  pig  about  six  weeks 
old  which,  dying  from  unknown  causes,  revealed  on  examination  an 
Ascaris  larva  in  a  fragment  of  lung  and  numerous  immature  ascarids 
in  the  intestine,  the  largest  about  two  inches  long. 

In  order  to  test  the  possibility  of  infecting  very  young  pigs  these 
investigators  used  two  young  pigs  from  a  sow  which  was  found  by  fecal 
examination  to  be  free  from  egg-producing  ascarids.  At  the  age  of 
about  two  weeks  one  of  these  pigs  was  given  a  large  number  of  Ascaris 
eggs  containing  motile-vermiform  embryos.  One  week  after  feeding 
the  eggs  this  pig  died;  the  other  pig  continued  in  good  health.  ''Exam- 
ination of  the  dead  pig,"  the  authors  state,  "revealed  a  pneumonia, 
with  numerous  petechial  hemorrhages  in  the  lung  tissue.  Numerous 
ascarid  larvse,  varying  in  length  from  0.7  to  1.2  mm.  in  length,  were 
found  in  the  lungs,  trachea,  and  pharynx;  none  in  the  liver,  spleen, 
esophagus,  small  intestine,  or  large  intestine."  As  to  conclusions  the 
authors  are  further  quoted  as  follows: 

"Stewart's  very  important  discoveries  concerning  the  behavior  of 


ASCARID.E  231 

Ascaris  larvae  in  rats  and  mice,  the  various  contributions  of  other  in- 
vestigators toward  the  sohition  of  the  problem  of  the  life  history  of 
Ascaris  lumbricoides  and  related  parasites,  and  our  own  experiences, 
appear  to  justify  certain  conclusions,  some  of  which  in  anticipation  of  a 
more  extended  statement  in  a  future  paper,  may  be  briefly  given  as 
follows : 

"The  development  of  Ascaris  lumbricoides  and  closely  related  forms 
is  direct,  and  no  intermediate  host  is  required. 

"The  eggs,  when  swallowed,  hatch  out  in  the  alimentary  tract; 
the  embrj'os,  however,  do  not  at  once  settle  down  in  the  intestine,  but 
migrate  to  various  other  organs,  including  the  liver,  spleen,  and  lungs. 

"Within  a  week,  in  the  case  of  the  pig  Ascaris,  the  migrating  larvse 
may  be  found  in  the  lungs  and  have  meanwhile  undergone  considerable 
development  and  growth. 

"From  the  lungs  the  larv£e  migrate  up  the  trachea  and  into  the 
esophagus  by  wa}'  of  the  pharynx,  and  this  migration  up  the  trachea 
ma}^  already  become  established  in  pigs,  as  well  as  in  artificiall.y  infected 
rats  and  mice,  as  early  as  a  week  after  infection. 

"Upon  reaching  the  alimentar}^  tract  a  second  time  after  their  passage 
through  the  lungs,  the  larvae,  if  in  a  suitable  host,  presumably  settle 
down  in  the  intestine  and  complete  their  development  to  maturity; 
if  in  an  unsuitable  host,  such  as  rats  and  mice,  they  soon  pass  out  of 
the  bod}'  in  the  feces. 

"Heavy  invasions  of  the  lungs  by  the  larvae  of  Ascaris  produce  a 
serious  pneumonia  which  is  frequently  fatal  in  rats  and  mice  and  ap- 
parenth'  caused  the  death  of  a  young  pig  one  week  after  it  had  been 
fed  with  numerous  Ascarid  eggs. 

"It  is  not  improl)able  that  ascarids  are  frequently  responsible  for 
lung  troubles  in  children,  pigs,  and  other  young  animals.  The  fact 
that  the  larvae  invade  the  lungs  as  well  as  other  organs  bej'ond  the 
alimentary  tract  and  can  cause  a  serious  or  even  fatal  pn^monia  in- 
dicates that  these  parasites  are  endowed  with  greater  capacity  for  harm 
than  has  heretofore  been  supposed. 

"Age  is  a  highly  important  factor  in  determining  susceptibility  to 
infection  with  Ascaris,  and  susceptibiUty  to  infection  greatly  decreases 
as  the  host  animal  becomes  older.  This,  of  course,  is  in  harmony  with 
the  well-known  fact  that  it  is  particularly  children  and  young  pigs 
among  which  infestation  with  Ascaris  is  common,  and  that  Ascaris  is 
relativel}'  of  rare  occurrence  in  adult  human  beings  and  in  old  hogs." 

ASCARIASIS 

Ascariasis  occurs  most  frequently  in  young  animals,  those  matured 
rarely  harboring  the  worms  in  such  numbers  as  to  bring  about  symptoms 


232  PARASITES  OF  THE  DOMESTIC  ANIMALS 

by  Avhich  the  condition  can  be  recognized.  Where  there  is  a  heavy  in- 
festation they  cause  injury  by  their  irritation  to  the  intestinal  mucosa. 
In  such  cases  they  may  become  massed  and  constitute  an  obstruction 
to  the  intestinal  lumen  sufficient  to  cause  stasis  of  the  contents  and  de- 
generative changes  in  the  intestinal  walls. 

The  ascarids  are  active  worms,  and  have  a  tendency  to  wander  to 
unusual  locations;  one  or  two  may  find  lodgment  in  accessory  organs  of 
the  intestines  b}--  way  of  their  ducts  and,  by  the  consequent  continuous 
irritation,  bring  about  results  of  a  serious  nature.  Verminous  fistulae 
may  be  thus  established,  or  there  iliay  be  abscess  formation  with  dis- 
charge of  pus  into  the  peritoneal  cavity,  followed  by  peritonitis.  In 
dogs  and  cats  especially,  the  worms  when  numerous  often  pass  to  the 
stomach  in  considerable  numbers,  setting  up  more  or  less  gastric  dis- 
turbance and  consequent  vomiting,  tha  expelled  material  generally 
containing  from  one  to  several  worms. 

Certain  foreign  investigators,  having  demonstrated  the  presence  of 
blood  in  ascarids,  have  concluded  from  this  that  these  worms  are  blood 
suckers.  Hall,  in  an  article  upon  the  parasites  of  the  dog  in  Michigan 
(Journal  of  the  American  Veterinary  Medical  Association,  June,  1917), 
states  that  an  ascarid  which  he  collected  from  the  feces  of  a  dog  showed 
a  pronounced  red  color  in  the  intestine,  evidently  due  to  blood.  As 
post-mortem  examination  of  the  dog  the  same  day  revealed  a  severe 
hemorrhagic  enteritis,  he  concludes  that  this  was  evidently  the  explana- 
tion for  the  blood  in  the  intestine  of  the  ascarid.  The  conditions  found 
in  this  case  suggest  the  possibility  of  similar  conditions  in  cases  regarded 
as  evidence  that  these  worms  are  blood  suckers, — a  conclusion  that  cer- 
tainly has  no  support  in  the  structure  of  the  ascarid's  mouth. 

There  seems  reason  to  doubt  that  ascarids  feed  upon  epithelial  cells, 
as  stated  by  some  authors.  Their  simple  intestinal  tube  is  restrictively 
modified  to  the  primary  function  of  absorption  of  nutriment  already 
made  in  a  certain  state  of  solution  by  the  digestive  juices  of  the  host, 
and  it  is  unlikely  that  such  digestive  powers  as  are  retained  by  the 
parasites  would  be  adapted  to  a  diet  of  epithelial  cells.  In  view  of  the 
fact  that  free  epithelial  cells  and  their  debris  are  contained  in  the  alimen- 
tary contents  of  the  host,  it  follows  that  such  material  would  be  in- 
gested along  with  the  alhnentary  matter  by  the  worms  and  would  be 
found  in  their  intestinal  contents. 

Aside  from  the  mechanical  injury  caused  by  the  ascarids,  there  are 
to  be  considered  the  effects  of  toxic  products  elaborated  by  their  bodies. 
These  may  be  practically  nil  or  considerable  according  to  the  character 
and  degree  of  the  infestation.  The  loss  of  condition  in  heavy  invasions 
can  probably  be  attributed  to  the  systemic  effect  of  these  poisons  com- 
bined with  that  of  the  catarrhal  enteritis.  It  seems  reasonable  to  con- 
clude that  the  deprivation  of  nutriment,  which  has  been  appropriated 


ASCARIDiE  233 

by  the  horde  of  parasites  in  the  ahmentary  canal,  is  also  a  morbid  factor. 
^Manifestations  of  the  toxemia  are  often  of  a  nervous  character;  there 
is  hyperrefiex  irritability,  and  con^^.llsions  are  a  not  infrequent  accom- 
paniment. 

In  general,  it  may  be  said  of  the  ascarids  that,  while  the}^  often  in- 
habit the  intestines  without  perceptible  indications  of  their  invasion 
other  than  their  occasional  expulsion  with  the  feces,  their  presence  con- 
stitutes a  condition  calling  for  treatment.  They  should  be  expelled  by 
the  administration  of  a  vermifuge,  in  most  cases  followed  bj'  a  purgative, 
and  their  bodies  collected  and  burned.  Not  only  should  the  treatment 
be  carried  out  for  considerations  pertaining  to  the  health  of  the  host, 
but  to  prevent  the  spreading  about  of  the  worms  with  their  eggs  and 
embrvos  to  infest  other  animals. 


Ascarids  of  the  Horse 

One  species  of  ascarid  inhabits  the  intestine  of  the  horse,  ass,  and  mule. 

Ascaris  equi  (A.  megalocephala,  A.  equorum).  Ascaridse  (p.  229). — 
This  is  the  largest  species  of  the  family.  The  bod}'  is  yellowish  white, 
about  the  thickness  of  a  lead  pencil,  and  somewhat  rigid.  The  head 
is  distinct  and  bears  three  lips.  The  caudal  extremit}-  of  the  male  is 
bordered  laterall}'  by  two  small  membranous  wings,  and  ventralh'  on 
each  side  there  are  80-100  papilla.  The  female  is  considerably  longer 
and  thicker  than  the  male.  The  vulva  is  situated  toward  the  anterior 
quarter  of  the  bod}'. 

Length  of  female:  15-30  cm.  (6-12  inches),  or  it  may  be  somewhat 
longer. 

Eggs  globular,  90-100  microns  in  diameter. 

The  species  is  found  only  in  Equida?,  and  lives  in  the  small  intestine, 
occasionally  found  in  oth(>r  organs  by  migration. 

Occurrence  and  Symptoms. — The  large  ascarid  is  verj'  common  in 
the  small  intestine  of  the  horse.  Unless  numerous,  they  do  not,  as  a 
rule,  perceptibly  affect  the  health  of  their  host,  often  the  only  evidence 
of  their  presence  being  the  voiding  of  one  or  more  of  the  wornis  with 
the  feces.  Young  annuals  do  not  bear  the  parasitism  so  well,  and  in 
moderate  to  hea^y  infestations  are  likely  to  manifest  serious  disturb- 
ances of  a  local  and  systemic  character. 

As  a  result  of  the  irritation  to  the  mucosa  there  is  a  chronic  intestinal 
catarrh,  and  this  may  be  accompanied  by  a  diarrhea  which  is  persistent, 
or  alternating  with  a  hard  dr}-  feces  covered  with  slimy  mucous  material. 
Colic  is  a  not  infrequent  s\nnptom,  and  there  may  be  intervals  of  more 
or  less  tympany.  The  worms,  when  massed  in  large  numbers,  are 
capable  of  bringing  about  an  obstruction  with  all  that  follows  such  a 
condition,  possibly  involving  intussusception  and  even  rupture. 


234  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Young  animals,  as  a  result  of  aggravated  ascariasis,  lose  condition 
and  there  is  arrest  in  their  development.  Due  largely  to  the  accumula- 
tion of  gas,  they  are  likel}^  to  become  more  or  less  pot-bellied,  the  activity 
of  the  skin  is  reduced,  and  the  coat  takes  on  a  dry,  harsh,  and  erect 
appearance.  The  alertness  and  inclination  to  play,  natural  to  foals  and 
young  horses,  is  lost,  and  the  animals  maj'  stand  about  looking  more  or 
less  dejected. 

Nervous  disturbances  are  occasionally  exhibited  by  vertigo  or, 
rarely,  by  epileptiform  or  tetanic  symptoms.  They  may  be  due  to  reflex 
irritation  or  to  toxic  products  from  the  bodies  of  living  worms,  to  which 
is  added  toxins  from  the  bodies  of  worms  which  are  dead  and  decompos- 
ing. 

Etiology. — Infection  occurs  by  the  introduction  of  eggs  and  embryos 
into  the  alimentary  canal  with  food  and  water.  Development  takes 
place  after  the  eggs  have  left  the  body  of  the  host  and  is  favored  by 
factors  of  warmth  and  moisture,  such  as  is  suppHed  by  moist  earth  and 
a  temperature  of  about  37°  C.  (98°  F.).  AVhile  segmentation  will  not 
proceed  under  low  temperature  conditions,  the  eggs  will  retain  their 
fertility  in  unfavorable  surroundings  for  a  comparatively  long  period 
and  will  develop  upon  reaching  a  favorable  environment.  Embryos 
within  the  eggs  appear  to  possess  considerable  resistance,  since  they 
have  been  observed  to  retain  their  vitality  in  dried  horse  manure  for 
six  months.  It  is  probable  that  infection  is  by  eggs,  and  that  few  em- 
br3^os  are  released  until  the  intestinal  contents  of  the  equine  host  is 
reached. 

Control. — Considering  the  persistent  vitality  of  the  eggs  and  em- 
bryos, it  is  especially  important  as  a  prophylactic  measure  that  as  man}^ 
as  possible  of  the  expelled  worms  be  collected  and  burned.  If  they  are 
permitted  to  find  their  way  to  the  manure  pile  or  to  be  scattered  about, 
some  of  the  myriads  of  eggs  contained  in  their  bodies  will  meet  with 
conditions  favorable  to  their  development  and  infect  other  horses. 
Precaution  should  be  taken  that  the  drinking  water  for  horses  does  not 
receive  contamination  from  collected  manure,  and  that  it  be  as  pure  and 
free  from  surface  drainage  as  possible. 

Treatment. — Treatment  should  be  preceded  by  the  withholding  of 
all  bulk}^  food  for  twenty-four  to  fortj'-eight  hours.  During  this  time 
the  animal  should  be  at  rest  and  may  be  given  bran  mashes,  to  which  a 
moderate  amount  of  grain  may  be  added  during  the  first  twenty-four 
hours  if  the  preparation  is  to  be  for  the  longer  period. 

While  the  preliminary  fasting  of  the  host  for  a  daj^  or  two  probably 
will  not  sufficiently  "starve"  the  parasites  to  be  of  any  value  as  an  aid 
in  their  expulsion,  it  permits  the  removal  of  the  bulky  portion  of  the 
intestinal  contents  and  prepares  for  a  diffuse  action  of  the  anthelmintic 
which  otherwise  would  not  be  possible. 


ASCARID.E  235 

Following  the  period  of  fasting,  give  two  to  four  ounces  of  oil  of  tur- 
pentine and  one  dram  of  oleoresin  of  aspidiuni,  in  a  pint  of  linseed  oil. 
If  necessary,  follow  twelve  hours  later  with  an  additional  pint  or  two  of 
linseed  oil. 

Tartar  emetic  in  two  to  three  dram  doses,  repeated  once  at  an  interval 
of  twelve  hours,  is  also  an  effectual  cxpellant.  This  is  best  administered 
with  linseed  meal  which  may  be  stii-red  into  a  small  bran  mash. 

These  doses  are  for  aged  horses  of  average  size,  and  are  to  be  modified 
according  to  age  and  somewhat  as  to  weight. 

The  vermifuge  is  in  most  cases  to  be  followed  twelve  to  twenty-four 
hours  later  by  a  purge,  preferabl}'  oleaginous,  but  this  should  not  be 
given  if  there  is  diarrhea,  and  may  not  be  necessary  if  the  animals  are 
upon  grass. 

Sulphate  of  iron  and  arsenic  are  remedies  which  have  also  been  recom- 
mended. If  arsenic  is  used,  it  should  be  given  in  the  form  of  powdered 
arsenous  acid  in  increasing  doses  for  about  two  weeks. 

Family  II.  Oxyuridae.  Xematoda  (p.  217). — This  family  is  consid- 
ered by  many  authors  as  belonging  with  the  Ascaridse.  Conspicuous 
characteristics  of  the  group  are  the  curved  anterior  portion  of  the  body 
and  the  elongated  and  attenuated  caudal  extremity  of  the  female.  The 
males  usually  have  but  one  spicule,  and  this  may  be  reduced  and  im- 
perfectly developed.    The  vulva  of  the  female  is  anterior. 

Oxyuris  equi  (O.  curvula,  O.  mastigodes).  Oxyuridse  (p.  235). — 
The  body  is  generalh'  white,  somewhat  thickened,  and  curved.  The 
mouth  is  provided  with  three  lips.  The  male  is  much  smaller  than  the 
female,  and  has  an  obtuse  caudal  extremity  which  bears  several  papillse, 
the  largest  of  which  sustains  a  caudal  bursa.  There  is  but  one  spicule 
and  this  is  straight  and  slender.  In  the  female  the  anterior  portion  of 
the  body  is  thickened  and  curved,  while  the  posterior  portion  is  at- 
tenuated to  a  point.  The  \ailva  is  about  8-10  nun.  (3/8  of  an  inch)  from 
the  mouth.  The  body  may  have  its  posterior  attenuated  portion  of 
variable  length  (Fig.  122) ;  in  some  individuals  this  is  very  much  pro- 
longed and  filamentous.  This  difference  has  led  some  authors  to 
describe  two  species  of  Ox>in'is  of  the  horse — O.  curvula  and  0.  7nasti- 
godes,  the  latter  including  those  with  the  extended  caudal  extremity. 
Railliet  has  demonstrated  that  forms  exist  possessing  all  intermediate 
gradations  between  those  with  very  short  and  those  with  very  long  tail 
extremities,  and  that  there  is  not,  therefore,  a  difference  of  true  specific 
character. 

Length  of  female,  4-15  cm.  (1  5/8-6  inches) ;  male,  al^out  1  cm.  (3/8  of 
an  inch). 

Eggs  oval  and  operculated;  85-95  microns  long,  40-45  microns  wide. 

The  species  inhabits  all  of  the  large  intestine  of  the  horse,  ass,  and 
mule. 


236  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Occurrence. — Oxyuris  equi  is  a  common  inhabitant  of  the  large  intes- 
tine of  the  horse.  The  condition  produced  by  these  worms  is  usually 
referred  to  as  oxyuriasis,  and  they  are  commonly  known  as  seat-worms 
or  pin-worms.  Often  they  are  observed  projecting  from  the  margin  of 
the  anus  to  which  they  adhere  while  depositing  their  eggs.  By  means 
of  a  sticky  substance  the  eggs  attach  about  the  skin  of  the  anus  and 
perineum  and  develop  embryos  within  two  to  three  days.  |  Later  the 
substance  by  which  they  are  fixed  to  the  skin  dries  and  the  eggs  drop 


Fig.  122. — Oxyuris  equi,  showing  varj'ing  lengths  of  posterior 
attenuated  portion. 

to  the  ground  where,  through  scattered  manure,  they  contaminate  the 
pasturage,  or,  if  the  animal  is  in  the  stable,  the  feed  ma}"  be  contam- 
inated in  the  same  manner. 

The  eggs  are  provided  at  one  end  with  a  sort  of  operculum  which,  on 
reaching  the  stomach,  is  digested  away.  The  released  embrj^os  are  then 
carried  with  the  alimentar}"  material  to  the  large  intestine  where  they 
reach  maturity. 

Effect. — The  offense  of  the  oxyurids  is  mainly  one  of  unsightliness. 
The}'  produce  itching  about  the  anus  which  may  become  intense,  causing 
the  animal  to  rub  the  parts  and  thus  bring  about  a  denudation  of  the 


ASCARID^  237 

tail  and  skin.  The  tail  is  frequently  agitated,  and  annojdng  habits  of 
"switching"  and  "line-hugging"  may  have  origin  from  this  source. 

In  aggravated  cases  there  may  be  loss  of  flesh  due  to  the  constant 
irritation  to  which  the  animal  is  subjected.  The  anus  becomes  swollen, 
flacid,  and,  on  defecation,  the  mucous  membrane  is  noticed  to  be  a  deep 
red. 

The  condition  is  readily  diagnosed  in  observing  the  protruding  or  ex- 
pelled worms.  The  sticky  yellowish-colored  deposit  about  the  anus  and 
perineum,  together  with  denudation  of  the  skin  and  base  of  the  tail 
by  rubbing,  indicates  the  presence  of  the  worms. 

Treatment. — Treatment  is  mainly  per  rectum.  Previous  to  the  ad- 
ministration of  vermifuge  cnemata  the  bowel  should  be  emptied  by  an 
injection  of  glycerin  and  water  or  of  warm  soap.y  water.  As  an  expellant, 
either  of  the  following  may  be  used:  (1)  Infusion  of  quassia,  one  to  two 
quarts;  (2)  infusion  of  tobacco,  one  ounce  to  one  quart  of  water;  (3) 
vinegar  in  soapy  water;  (4)  one  quart  of  a  one  per  cent,  solution  of 
lysol;  (5)  one  to  two  ounces  of  oil  of  turpentine  shaken  up  in  a  quart  of 
Ume  water  and  linseed  oil;  (6)  mercurial  ointment  repeatedly  applied 
to  the  borders  of  the  anal  orifice  is  also  of  service.  The  injections  are 
best  given  through  a  rubber  siphon. 

As  developing  worms  from  ingested  eggs  ma}'  be  in  the  intestines  too 
far  forward  to  be  acted  upon  by  the  enemata,  it  is  well  to  supplement 
this  treatment  with  the  administration  of  a  vermifuge  as  recommended 
for  the  large  ascarids  of  the  small  intestine. 

Treatment  is  to  be  repeated  at  intervals  of  four  to  six  days  until 
indications  of  the  presence  of  the  worms  have  disappeared. 

The  adhering  deposit  about  the  rectum  and  perineum  should  be 
regularly  removed  and  so  disposed  of  that  the  contained  eggs  cannot 
reinfect. 

AsCARIDiE    OF   THE    DoG   AXD    CaT 

One  species  of  ascarid  is  connnon  in  the  dog  and  cat,  although  some 
authors  recognize  two— Belascaris  marginata  of  the  dog,  and  B.  mystax 
of  the  cat.  Other  than  being  a  little  smaller,  the  ascarid  of  the  cat 
scarcely  differs  from  that  of  the  dog,  and  at  the  present  time  the  ma- 
jority of  helminthologists  consider  the  difference  as  one  of  variety  only. 

A  much  less  conuuon  species  infesting  dogs  in  this  country  is  Tox- 
ascaris  limhata. 

Belascaris  marginata  (Ascaris  marginata,  A.  mystax,  Belascaris 
mystax,  B.  cati).  Ascaridee  (p.  229).— The  body  is  white,  or  reddish 
white.  The  head  is  usually  curved  and  is  provided  on  each  side  with  a 
membranous  wing,  giving  the  appearance  of  an  arrow-head  (Fig.  123). 
On  the  curved  tail  of  the  male  there  are  two  small  membranous 
lateral  wings  and  twenty-six  papillae  on  each  side.    The  \'ulva  of  the 


238 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


female  is  situated  toward  the  anterior  quarter  of  the  body.  The  tail 
is  obtuse. 

Length  of  female,  9-14  cm.  (3  1/2-5  1/2  inches);  male,  5-10  cm.  (2-4 
inches). 

Eggs  globular,  75-80  microns  in  diameter. 

Infests  the  small  intestine. 


Fig.  123. — Belascaris    marginata:    A, 
male;  C,  female,  natural  size. 


head,    enlarged;    B, 


Toxascaris  limbata  (Toxascaris  marginata).  Ascaridse  (p.  229). — 
The  body  is  firm  and  whitish  or  pale  red  in  color.  The  cephalic  wings 
are  long,  narrow,  and  somewhat  lanceolate.  The  spicules  of  the  male 
are  not  quite  equal. 

Length  of  female,  6.5-10  cm.  (2  1/2-4  inches) ;  male,  4-6  cm.  (1  1/2- 
2  3/8  inches). 

The  eggs  are  75  to  85  microns  in  diameter. 

Parasitic  in  the  intestines  of  the  dog. 

Occurrence  in  the  Dog. — Belascaris  marginata  is  most  often  found 
in  young  dogs  of  three  to  four  months.  It  is  probable  that  about  thirty 
per  cent,  of  all  puppies  harbor  the  worms  in  more  or  less  numbers  in 


ASCARID^  239 

their  small  intestine.  The}'  frequently  enter  the  stomach  and  cause 
vomiting,  the  expelled  material  often  containing  several  worms.  Other- 
wise the  S}iiiptoms  are  much  hke  those  caused  by  the  presence  of  tape- 
worms. There  is  emaciation,  enlarged  abdomen,  and  irregular  appetite. 
There  may  be  diarrhea  or  constipation,  and,  finall}',  epileptiform  or 
rabiform  seizures.  B^^  massing  in  the  small  intestine,  they  may  induce 
invagination  and  fatal  obstruction  to  the  alimentary  matter. 

Necropsies  upon  dogs  which  have  died  from  ascariasis  reveal  the 
lesions  of  an  intense  hemorrhagic  enteritis,  with  tumified  mucosa,  show- 
ing small  ulcerative  points  and  involvement  of  the  submucous  tunics. 

Treatment. — (1)  Powdered  areca  nut,  two  grains  to  each  pound  of 
bod^'-weight,  ma^'  be  given  shaken  up  in  a  little  milk.  (2)  Santonin  is 
one  of  the  most  frequently  used  remedies.  The  dosage  should  be  care- 
fully graded,  giving  one-eighth  of  a  grain  per  pound  of  body-weight,  the 
dose  in  no  case  to  exceed  three  grains.  It  ma}'  be  administered  sus- 
pended in  milk  or  combined  with  one-fourth  to  two  grains  of  calomel, 
made  into  a  pill.  (3)  Fifteen  minims  to  one  dram  of  oleoresin  of  as- 
pidium,  singly  or  combined  with  a  grain  of  areca  nut,  per  pound  of  body- 
weight,  may  be  given  in  capsule.  (4)  Benzene,  in  fifteen  drop  to  one 
dram  doses  in  oil,  has  been  recommended. 

The  anthelmintic  should  be  administered  in  the  morning  after  a 
twelve  hours'  fast.  If  the  bowels  are  not  ah'eady  freely  active,  it  is 
well  to  follow  the  remedy  a  few  hours  later  with  a  purgative  of  castor 
oil  or  syrup  of  buckthorn.  Care  should  be  taken  in  the  administration 
of  these  drugs  to  to}'  puppies.  Santonin,  especially,  should  not  be  given 
until  they  are  at  least  eight  weeks  old;  under  that  age,  a  simple  laxative 
will  often  bring  away  quite  a  number  of  the  worms. 

If  vomiting  occurs  after  giving  the  medicine,  allow  an  interval  of 
two  or  three  days  before  repeating;  then  precede  by  a  stomach  sedative 
of  bismuth  or  a  small  dose  of  cocaine. 

Occurrence  in  the  Cat. — Ascariasis  of  the  cat  does  not  sufficiently 
differ  from  that  of  the  dog  to  merit  a  special  description.  As  in  the  dog, 
the  worms  are  more  likely  to  infest  young  animals,  though  cats  seem 
to  bear  the  invasion  better. 

Remedies  recommended  for  the  dog  will  serve  as  well  for  the  cat, 
though  the  peculiar  intolerance  of  these  animals  should  be  taken  into 
consideration  in  the  selection  and  dosage.  (1)  Cusso,  fifteen  to  thirty 
grains,  is  relativel}-  safe,  but  is  likeh'  to  cause  vomiting.  (2)  Oleoresin 
of  aspidium,  minims  fifteen  to  twenty,  may  be  given  in  milk. 

ASCARID.E    OF   THE    HoG   AND   ShEEP 

Ascaris   lumbricoides    (A.    suis,    A.    suum,    A.    ovis).     Fig.    125. 

Ascaridse  (p.  229). — The  head  has  three  strong  lips,  the  lateral  sides  of 


240 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Fig.  124 
Ascaris  lumbricoides, 
with  shell  and  albu- 
rn i  n  o  u  s  envelope 
(copied  from  Braun's 
"Animal  Parasites  of 
Man"). 


which  are  generally 
denticulate.  The  body 
is  white,  firm,  and  elas- 
tic. The  males  have 
two  spicules  and  numer- 
ous papillae  anterior  and 
posterior  to  the  anus. 
The  vulva  of  the  female 
is  situated  toward  the 
Egg  of  anterior  third  of  the 
body. 

Length  of  female,  20- 
25  cm.  (8-10  inches); 
male,  15-17  cm.  (6-6  3/4 
inches) . 

Eggs,  oval,  60-75  microns  long  by  40-58 
microns  wide.    The  shell  is  mammillated. 

In  its  adult  state  this  worm  lives  in  the 
intestines  of  the  hog  and  sheep,  and  also  of 
man. 

The  ascarid  of  the  hog  and  sheep  and 
that  of  man  so  closely  resemble  each  other 
that  a  number  of  authors  now  consider 
them  as  one  species;  others  distinguish  a 
specific  difference,  claiming  that  the  ascarid 
of  the  pig  differs  from  the  human  ascarid 
in  being  thinner,  having  the  longitudinal 
strise  closer,  spicules  less  sharp,  and  ova 
smaller.  It  would  seem,  however,  that  such 
slight  differences  should  be  regarded  as  of 
no  more  than  varietal  importance. 

Heavy  invasions  of  these  worms  in  the 
intestines  of  hogs  bring  about  the  con- 
ditions such  as  have  alread,y  been  described 
in  aggravated  intestinal  helminthiasis.  In 
young  pigs  especially,  there  is  general  un- 
thrift,  and  emaciation  may  become  quite 
advanced.  There  is  usually  a  cough,  and 
this  is  likely  to  be  accompanied  by  occa- 
sional vomiting.  The  pig  shows  a  pecu- 
liar restlessness,  wandering  about  without 
apparent  motive  and  emitting  cries  indica- 
tive of  colicky  pains.  The  lumen  of  the 
intestines    may    be    obstructed    by    the 


Fig.  125.  — -  Aseari 
coides,  male  at  right, 
left,  natural  size. 


i     luml^ri- 
female  at 


ASCARID.E  241 

worms  in  mass  with  the  usual  sequence  of  localized  inflammatory 
changes. 

Invasion  of  the  Ijile  duct  of  pigs  with  these  ascaiids  is  of  frequent 
occurrence  and  may  often  bring  about  a  fatal  result.  Autopsies  at  the 
Pennsylvania  State  Laboratories  upon  pigs  dead  from  this  parasitism 
have  in  some  cases  revealed  the  common  bile  duct  literally  packed  and 
occluded  with  the  worms. 

Treatment. — Treatment  is  mainly  proph.vlactic.  Thorough  clean- 
ing up,  Ixuning  of  litter,  and  a  liberal  application  of  disinfectants  is 
essential,  and  the  source  of  water  supply  and  drainage  should  be  looked 
to.  Infested  pigs  should  be  isolated  and  precautions  taken  against 
reinfection. 

Medicine  is  best  administered  in  milk,  or  other  semi-fluid  media,  fed 
to  the  pigs  as  a  whole,  the  dosing  of  individual  pigs  being  a  somewhat 
discouraging  task.  It  is  better  to  separate  the  pigs  for  this  purpose  into 
groups  of  not  more  than  ten  of  nearly  equal  size,  otherwise  the  largest 
and  most  aggressive  will  get  more  than  their  portion. 

As  a  vermifuge,  pulverized  areca  nut  may  be  usetl,  the  dose  being 
approximately  one  grain  to  each  pound  of  body-weight.  This  should 
l^e  followed  by  a  pui'gative,  preferably  saline,  the  dose  graded  according 
to  size  of  pigs,  and  administered  as  al)ove.  Benzene,  in  one  to  three 
dram  doses  mixed  with  the  food,  has  been  recommended  as  effective. 

When  individual  treatment  of  young  pigs  is  resorted  to,  one  to  five 
grains  of  calomel,  given  in  milk  and  followed  by  castor  oil,  will  in  many 
cases  be  sufficient  to  dislodge  the  worms.  For  older  pigs  it  is  better  to 
follow  the  calomel  with  a  saline  evacuant. 

Ascariasis  of  Sheep. — Ascarids  are  rarely  found  in  sheep.  In  the 
Bureau  of  Animal  Industiy  Collection  there  are  specimens  of  ascarids 
obtained  from  sheep  at  Blairsville,  Pa.,  Brookings,  South  Dakota,  and 
Bethesda.  Aid.     (Bulletin  127.  1911.) 

ASCARID.E    OF   THE    Ox 

Ascaris  vitulorum.  Ascaridse  (p.  229). — The  head  is  small  and  has 
three  lips  which  are  somewhat  enlarged  at  the  base.  The  body  is  white 
or  may  be  reddish  white.  The  caudal  extiemity  of  the  male  has  two 
rows  of  papillae,  10-15  in  each ;  these  are  lateral  and  pre-anal.  The  vulva 
of  the  female  is  situated  toward  the  anterior  sixth  of  the  body. 

Length  of  female,  22-30  cm.  (8  1  '2-1 1  3/4  inches) ;  male,  15-20  cm.  (6- 
7  3/4  inches). 

Eggs,  75-80  microns  in  diameter. 

Lives  in  the  intestine  of  calves;  rare  in  adult  cattle. 

This  worm  is  most  frequently  met  with  in  parts  of  Southern  Europe, 
where  it  is  found  hi  rather  large  mmibers  in  the  small  intestine  of  calves 
slaughtered  for  veal. 


242 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Heterakiasis  of  Chickens 

Family  III.  Heterakidae.  Nematoda  (p.  217).— This  family,  like 
the  Oxyuridae,  is  placed  by  some  authors  with  the  Ascaridse.  The 
t3Te-genus  is  Heterakis,  of  which  two  species  infesting  chickens  are  to 
be  described. 

1.  Heterakis  perspicillum  (H.  inflexa).  Fig.  126.  Heterakida 
(p.  242).— The  mouth  has  three  lips  of  unequal  size,  the  dorsal  lip  the 
largest.     The  body  is  yellowish  white.     The  caudal  extremity  of  the 


Fig.    126. — Heterakis    perspicillum:    a,  female;    b,  male; 
c,  Heterakis  vesicularis.    All  natural  size. 

male  terminates  obliquely,  and  is  provided  on  each  side  with  a  mem- 
branous wing  and  ten  papillae.  The  two  spicules  are  nearly  equal. 
On  the  ventral  surface  anterior  to  the  anus  there  is  a  rounded  sucker. 
The  caudal  extremity  of  the  female  is  straight,  conical,  and  terminates 
in  a  point.    The  vulva  is  located  in  the  anterior  part  of  the  body. 

Length  of  female,  6-12  cm.  (2  1/2-4  3/8  inches) ;  male,  3-8  cm.  (1  1/4- 
31/8  inches). 

Eggs,  elliptical,  75-80  microns  in  length  by  45-50  microns  in  width. 

The  species  is  common  in  the  small  intestine  of  the  chicken,  turkey, 
and  guinea  fowl. 

2.  Heterakis  vesicularis  (H.  papillosa).  Fig.  126.  Heterakidae 
(p.  242). — The  mouth  has  three  small  lips  of  equal  size.    The  body  is 


ASCARID^  243 

white  and  attenuated  at  its  two  extremities.  The  caudal  extremity  of 
the  male  is  straight,  with  lateral  wings,  and  twelve  papillae.  The  spicules 
are  unequal.  The  caudal  extremity  of  the  female  is  very  slender.  The 
vulva  is  posterior  to  the  middle  of  the  body. 

Length  of  female,  10-15  mm.  (3/8-5/8  of  an  inch);  male,  7-13  nmi. 
(5/16-1/2  inch). 

Eggs,  elliptical,  63-71  microns  in  length  by  38-48  microns  in  width. 

This  species — nmch  smaller  than  the  preceding — is  also  common, 
and  lives  in  the  cecum  of  the  chicken,  turkey,  guinea  fowl,  pheasant, 
pea-fowl,  duck,  and  goose. 

Symptoms. — Heterakiasis  of  chickens  is  usually  caused  by  Heter- 
akis  perspicillum.  In  general,  the  presence  of  the  worms  is  indicated 
by  dullness  and  an  indisposition  to  move  about.  Though  the  appetite 
may  be  preserved,  there  is  more  or  less  emaciation,  the  feathers  become 
erect  and  lusterless,  and  the  wings  droop.  If  the  condition  is  aggravated 
the  symptoms  progress,  diarrhea  sets  in,  the  appetite  dwindles,  the 
comb  becomes  pale,  and  the  creature,  with  eyes  half  closed,  remains 
huddled  up  and  unmovable  until  death  comes  to  its  relief. 

In  such  cases  necropsy  will  reveal  the  lesions  of  a  subacute  enteritis, 
and  frequently  the  presence  of  numerous  tapeworms  as  well  as  round- 
worms. 

Intestinal  helminthiasis  in  fowls  is  often  an  accompaniment  to  diseases 
presenting  somewhat  similar  spnptoms,  therefore  care  should  be  taken 
that  a  coincidence  does  not  mislead,  and  that  such  causes  of  high  mortal- 
ity as  fowl-cholera  be  not  overlooked. 

Treatment. — Sick  birds  should  be  isolated  in  clean  bright  quarters 
and  their  droppings  fvequentl}'  removed  and  destroyed.  As  medicinal 
treatment,  probably  areca  nut  is  most  effectual.  This  may  be  given  to 
full-grown  birds  in  doses  of  eighteen  to  twenty-four  grains,  administered 
in  bolus  made  up  with  Hnseed  meal  or  bread.  Calomel,  one  to  two  grains, 
given  in  the  same  manner,  has  also  been  recommended. 

Essentially,  thorough  cleaning  up  and  disinfection  are  necessary  to 
the  successful  eradication  of  the  parasites. 


CHAPTER  XX 
NEMATODA.  FAMILY  IV.  FILARIID^ 

The  Thread-like  Worms 

Nematoda  (p.  217). — The  nematodes  of  this  family  have  the  body 
long  and  filiform  (Figs.  127  and  129).  The  shape  of  the  mouth  varies; 
it  may  be  provided  with  lips  or  it  may  be  surrounded  with  papillae. 
The  esophagus  is  slender,  without  posterior  bulb.  The  males  may  have 
one  spicule  or  two  unequal  spicules,  and  the  tail  is  generally  spirally 
rolled.  The  females  have  two  ovaries;  vulva  usually  anterior  to  the 
middle  of  the  body.  The  embryonal  development  is  usualty  within  the 
body  of  the  female. 

Parasitism. — The  filarise  live  as  parasites  chiefly  in  serous  cavities 
of  the  body,  blood  and  lymph  channels,  and  in  the  submucous  and  sub- 
cutaneous connective  tissues.  They  may  be  found  in  most  any  part  of 
the  body,  but  do  not  commonly  inhabit  the  lumen  of  the  alimentary 
canal. 

The  parasitism  of  the  filariae  produces  a  condition  in  their  hosts  known 
as  filariasis. 

FiLARIID.E    OF   THE    HORSE 

1.  Setaria  labiato-papillosa  (Filaria  equina).  Fig.  127.  Filariidse 
(p.  244). — ^The  Iwdy  is  long,  white,  filiform,  and  attenuated  at  both 
ends.  The  integument  has  fine  transverse  striations.  The  mouth  is 
small,  circular,  and  provided  with  a  chitinoiis  ring,  the  border  of  which 
is  divided  by  four  salient  papilla?.  Outside  of  this  on  each  side  are  two 
small  papillae  in  the  form  of  small  spines.  The  tail  of  the  male  is  rolled 
up  spirally  and  presents  on  each  side  four  preanal  and  four  or  five 
postanal  papilla?.  There  are  two  spicules.  The  tail  of  the  female  is 
slightly  spiral  and  is  terminated  by  a  papilla.  The  vulva  is  situated 
near  the  anterior  extremity. 

Length  of  female,  9-12  cm.  (3  1/2-4  3/4  inches);  male,  6-8  cm. 
(2  3/8-3  1/8  inches). 

Newly  hatched  embryos  are  about  280  microns  long  by  7  microns  in 
breadth.    The  embryonic  development  is  within  the  body  of  the  female. 

Occurrence. — This  species  is  most  often  met  with  in  the  peritoneal 
cavity — more  rarely  in  the  pleural  cavity  of  the  horse,  ass,  and  mule. 
The  worms  are  especially  fitted  for  migrations  by  their  slender  and 
attenuated  bodies,  and,  from  their  location  in  serous  cavities,  may  pass 


FILARIID.E 


^245 


to  the  subperitoneal  and  subpleural  connective  tissues  or  to  the  mus- 
cular septa,  scrotum,  or  other  parts  of  the  body.  The  small  filarise 
occasionally  found  in  the  anterior  chamber  of  the  eye  are  considered 
l)y  most  authors  to  belong  to  this  species. 

Efifect. — Unless  present  in  exceptionally  large  numbers,  these  worms 
do  not  produce  serious  disturbance.     Their  presence  in  the  eye  may 
cause  inflammation  with  bulging  and  opacity  of  the 
cornea  for  the  relief  of  which  operative  measures  must 
be  resorted  to. 

Nothing  definite  is  known  as  to  the  evolution  of 
this  nematode;  the  fact  that  the  embryos  have  been 
olDserved  in  the  blood  of  the  horse,  points  to  the 
probability  that  they  pass  to  the  body  of  a  blood- 
sucking insect. 

2.  Habronema  megastoma  (Spiroptera  megas- 
toma).  Filariidae  (p.  244). — This  is  a  small  nematode 
with  whitish  colored  body  attenuated  at  the  extremi- 
ties. The  cephalic  portion  is  separated  from  the 
remainder  of  the  body  by  a  constriction,  and  is  pro- 
vided with  four  chitinous  lips.  The  mouth  is  con- 
tinued by  an  infundibuliform  pharynx.  The  caudal 
extremity  of  the  male  is  rolled  and  bears  two  lateral 
wings, each  sustained  by  four  preanal  and  one  pos- 
tanal papillae.  There  are  two  spicules.  The  tail  of 
the  female  is  straight  and  obtuse;  vulva  situated  to- 
ward anterior  third  of  the  body. 

Length  of  female,  10-13  mm.  (3/8  of  an  inch); 
male,  7-10  mm.  (1/4-  3/8  of  an  inch). 

Eggs,  elongate,  33  microns  long  by  8  microns  in 
breadth.  Development  and  hatching  are  within  the 
body  of  the  female  (ovoviviparous).  The  liberated 
embr3'os  measure  600-700  microns  in  length. 

The  life  history  is  not  known. 

This  species  infests  the  submucosa  of  the  stomach 
of  the  horse.  They  are  usually  in  the  right  sac,  and 
their  presence  may  be  recognized  l)y  oval  or  rounded 
prominences  varying  in  size  from  that  of  a  hazel  nut 
to  that  of  a  walnut.  The  mucous  membrane  covering  the  tumors  is 
unaltered  with  the  exception  of  a  number  of  perforations  at  the  summits 
which  communicate  with  the  contained  cavities.  Within  the.se  cavities 
are  lodged  the  worms  which,  on  pressure  upon  the  tumor,  are  extruded 
together  with  a  purulent  matter. 

It  is  probable  that  the  worms  reach  their  subnmcous  lodgment  as 
embrA^os  b}'  way  of  the  gastric  ciypts,  the  irritation  of  their  presence 


Fig.  127. — .Setaria 
labiato-papillosa.male 
at  loft,  female  at  right. 


246  PARASITES  OF  THE  DOMESTIC  ANIMALS 

setting  up  proliferative  changes  with  the  formation  of  prominences. 
Outwardly  the  tumors  are  limited  by  the  muscular  layers  of  the  stom- 
ach, the  connective  tissue  involved  being  that  of  the  submucosa.  In 
old  tumors  the  walls  become  of  a  dense  fibrous  character,  taking  some- 
what the  consistency  of  cartilage.  In  these  no  worms  may  be  found,  or 
there  may  be  a  few  of  their  disintegrated  bodies  contained  in  a  small 
amount  of  purulent  material. 

Essentially  the  presence  of  such  parasites  can  only  be  revealed  post- 
mortem. The  tumors  are  not  as  a  rule  numerous,  and  do  not  seem  to 
cause  any  serious  disturbance. 

The  manner  of  infestation  by  the  worms  is  not  known,  nor  is  it  known 
whether  they  multiply  within  the  tumors. 

3.  Habronema  microstoma  (Spiroptera  microstoma).  Filariidse 
(p.  244). — This  species  is  larger  than  the  preceding  and  may  also  be  dis- 
tinguished from  it  by  the  absence  of  the  constriction  behind  the  cephalic 
extremity.  The  mouth  presents  a  notch  on  each  side,  and  there  are  two 
lateral  lips.  The  tail  of  the  male  is  rolled  spirally,  has  two  lateral  wings, 
and  a  varying  number  of  papillse.  There  are  two  spicules.  The  vulva 
of  the  female  is  situated  near  the  anterior  third  of  the  body. 

Length  of  female,  12-27  mm.  (1/2-1  inch); male,  10-20  mm.  (3/8-3/4 
of  an  inch). 

The  eggs  are  elongate  and  truncated  at  their  extremities.  They  are 
45-49  microns  long  by  16  microns  wide.  Development  and  hatching 
are  within  the  body  of  the  female  (o vo viviparous) .  The  hberated  em- 
bryos measure  90-98  microns  in  length. 

The  life  history  is  not  known. 

Occurrence. — Post-morten  inspection  of  the  interior  of  the  horse's 
stomach  will  occasionally  reveal  the  presence  of  these  worms  in  such 
quantity  as  to  cause  an  undulating  movement  of  the  contents  of  the 
organ,  due  to  their  active  motion.  While  most  of  the  worms  are  free, 
many  may  be  found  with  their  heads  inserted  in  the  gastric  crypts  of 
the  right  sac.  More  or  less  inflammatory  disturbance  of  the  mucosa 
may  thus  be  set  up,  in  some  cases  involving  ulceration. 

As  in  the  case  of  the  preceding  species,  infestation  with  these  worms 
can  only  be  revealed  when  they  are  brought  to  light  after  the  death  of 
the  host.  Where  a  chronic  gastric  disturbance  is  suspected  to  be  due 
to  parasites  of  the  stomach,  one  or  two  ounces  of  oil  of  turpentine  may 
be  given  in  two  or  three  pints  of  linseed  oil. 

FiLARiiD^  OF  Sheep  and  Cattle 

1.  Gongylonema  scutata  (Spiroptera  scutata).  Fig.  128.  Filariidse 
(p.  244). — The  body  is  long  and  filiform,  white  or  yellowish  white, 
striated  transversely^,  and  slightly  attenuated  toward  the  extremities. 


FILARIID.E 


247 


The  mouth  has  two  lateral  and  four  smaller  submedian  papilla.  On 
the  anterior  1  to  3  mm.  of  the  body  are  rounded  or  oval  cuticular  tuber- 
cles arranged  more  or  less  regularly  in  rows.  The  tail  of  the  male  is 
rolled  up  and  has  two  asynunetrical  wings  and  two  spicules.  The  \ailva 
of  the  female  is  situated  in  front  of  the  anus. 

Length  of  female,  8-14  cm.  (3  1/8-5  1/2  inches);  male,  3-5  cm.  (1  1/4 
2  inches). 

The  eggs  are  oval.     Embrj-onal  development  is  within  the  body  of 
the  female. 

Occurrence.— This  is  a  common  species  found  in  a  large  percentage 


.5    <^l 


Fig.  128. — Gongyloncma  scutata:  a,  anterior  portion  of  body, 
dorsal  view;  b,  posterior  extremity  of  female;  c,  posterior  ex- 
tremity of  male,  ventral  view;  d,  same  viewed  obliquelj^  from 
left  side, — all  enlarged  (after  Ransom,  from  Neumann,  Bull. 
No.  127,  Bureau  An.  Ind.,  U.  S.  Dept.  Agr.). 


of  sheep  and  cattle  slaughtered  in  the  abattoirs  of  this  country  and 
Europe.  It  has  also  been  observed  in  the  horse  and  in  the  mouth  and 
pharynx  of  pigs.  It  inhabits  the  mucosa  of  the  esophagus,  usually  in  the 
thoracic  portion  where  it  is  lodged  just  l^encath  the  epithelium.  Its  body 
runs  parallel  to  the  long  axis  of  the  organ  and  is  disposed  in  a  spiral  man- 
ner, givmg  somewhat  the  appearance  of  the  wool-fiber  of  a  merino  sheep. 
There  is  no  apparent  effect  upon  the  health  of  animals  harboring  this 
worm.  Its  only  economic  importance  seems  to  be  in  rendering  the 
esophagus  undesirable  for  use  in  meat  food  products. 


248  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Experiments  by  Ransom  and  Hall  have  shown  that  dung  beetles  and 
croton  bugs  fed  upon  the  eggs  of  Gongylonema  scutata  become  infested 
with  an  encysted  larval  stage  of  the  parasite.  Evidence  is  thus  furnished 
that  the  mammalian  hosts  of  the  worm  become  infested  as  a  result  of 
swallowing  insects  bearing  the  encysted  larvse. 

2.  Filaria  labiato-papillosa  (F.  cervina).  Filariida^  (p.  244). — This 
species  resembles  Setaria  labiato-papillosa  of  the  horse,  but  differs  from 
it  in  the  absence  of  transverse  striations  of  the  integument  and  in  the 
caudal  papilla  of  the  female,  which  form  a  terminal  cluster  of  small 
blunt  points,  anterior  to  which  are  two  thick  conical  papillae. 

Length  of  female,  6-12  cm.  (2  3/8-4  3/4  inches);  male,  4-6  cm. 
(1  1/2-2  3/8  inches). 

Development  and  hatching  is  within  the  body  of  the  female  (ovovi- 
viparous).    The  freed  embryos  are  140-230  microns  in  length. 

This  nematode  of  the  ox  and  deer  is  found  almost  exclusively  in  the 
peritoneal  cavity.  It  does  not  appear  to  have  any  effect  upon  the  health 
of  its  hosts.  A  worm  occasionally  found  in  the  eye  of  the  ox  is  con- 
sidered as  belonging  with  this  species. 

FlLARIID^    OF   THE    DoG 

1.  Dirofilaria  immitis  (Filaria  immitis).  Fig.  129.  Filariidae 
(p.  244). — The  body  is  white,  long,  decidedly  thread-like,  with  ends 
having  an  obtuse  appearance.  The  mouth  is  small  and  surrounded  by 
six  indistinct  papilla?.  The  posterior  extremity  of  the  male  is  slender, 
rolled  spirally,  and  bears  two  small  lateral  wings.  There  are  two 
spicules.    The  posterior  extremity  of  the  female  is  obtuse. 

The  female  is  25  to  30  cm.  in  length  and  about  1  mm.  in  diameter 
(9  3/4  inches  by  1/32  of  an  inch).  The  length  of  the  male  is  12-18  cm. 
(4  3/4-7  inches). 

The  embryos  are  developed  and  hatched  in  the  body  of  the  female 
(ovoviviparous).  As  they  enter  the  circulation  they  measure  285- 
295  microns  in  length  and  have  a  diameter  of  about  5  microns.  The 
anterior  extremity  is  obtuse,  the  posterior  extremity  attenuated  and 
slender. 

Occurrence. — Hematic  filariasis  of  dogs,  produced  by  this  species, 
has  been  most  frequently  met  with  in  China  and  Japan,  about  fifty 
per  cent,  of  all  dogs  in  the  latter  country,  it  is  estimated,  being  affected. 
It  occurs  also  in  other  countries,  including  North  America. 

The  usual  seat  of  invasion  is  the  blood-vascular  system,  particularly 
the  right  ventricle  of  the  heart,  the  pulmonar}^  arteries  being  more 
rarely  involved.  Not  infrequently  mature  filarrae  are  found  in  the  sub- 
cutaneous connective  tissue.  In  the  heart  and  large  arteries  the  worms 
may  be  found  in  a  tangled  mass  containing  hundreds  so  interlaced  as  to 
make  it  difficult  to  extricate  single  individuals. 


FILARIID.E 


249 


Pathogenesis. — The  disturbances  caused  l)y  the  presence  of  the 
mature  filarial  are  principally  mechanical.  Dependinjj:  upon  their 
number,  they  more  or  less  interfere  with  the  circulation,  in  some  cases 
forming-  a  thrombus  which  may  give  rise  to  emboli  in  the  branches  of 
the  pulmonaiy  artery.  In  such  cases  necrotic 
areas  in  the  lungs  with  abscess  formation  may 
result. 

The  larvae,  probably-  by  their  toxic  protlucts. 
bring  about  anaemia  with  a  leucocytosis  which, 
depending  upon  the  number  of  the  parasites 
present,  may  be  more  or  less  pronounced.  As 
a  result  of  the  invasion  of  the  heart,  local  mani- 
festations of  endocarditis  are  to  be  looked  foi-. 
The  heart's  action  is  variouslv  disturbed,  lead- 
ing to  dropsical  conditions  accompanied  l)y 
cough  and  dyspnoea.  Nephritis  and  convul- 
sions may  develop  as  a  later  complication.  If 
the  condition  terminates  in  death,  it  is  usually- 
from  paralysis  of  the  heart  or  a  general  weakness 
followed  by  complete  paralysis. 

Diagnosis. — The  parasites  ma}-  be  present 
without  causing  observable  manifestations, 
while,  on  the  other  hand,  no  line  of  clinical 
symptoms  can  with  certainty  be  attril)uted  to 
such  invasion.  A  more  precise  diagnosis  can 
usually  be  made  by  microscopic  examination  of 
the  blood  for  demonstration  of  the  jiresence  of 
the  larvae.  Under  low  magnification,  a  drop  of 
infected  blood  placed  between  a  slide  and  a 
coverslip  will  reveal  fine  worm-like  larvae  in 
snake-like  movements  between  the  corpuscles. 
It  is  claimed  by  most  investigators  that  they 
appear  in  greatest  numbers  in  the  peripheral 
circulation  during  the  night,  and,  therefore,  that 
amination  is  best  drawn  during  these  hours. 

Infection. — The  manner  of  natural  infection  with  this  parasite  has 
not  yet  been  satisfactorily  determined.  Manson  concluded  from  his 
investigations  that  the  larvae  of  Filaria  bancrofti  (F.  sanguinis  hominis) — 
a  blood  parasite  of  man  resembling  the  species  under  consideration — 
pass  into  the  digestive  tract  of  a  mosquito  (Culex)  when  it  sucks  the 
blood  of  an  affected  person.  Later  the  mosquito,  after  depositing  its  eggs 
upon  the  water,  dies,  the  body  disintegrates,  and  the  lai-val  filariae  are  lib- 
erated, man  becoming  infected  by  drinking  the  water  thus  contaminated. 
It  has  been  held  that  Dirofilaria  immitis  has  a  similar  development. 


Fig.  129. — Dirofilaria  im- 
mitis; male  at  loft,  female  at 
right, — natural  size  (after 
Railli.'t). 

blood  for  such  ex- 


250  PARASITES  OF  THE  DOMESTIC  ANIMALS 

According  to  Noe,  some  of  the  larvae  are  taken  with  the  infected  blood 
into  the  bodies  of  blood-sucking  insects.  From  the  intestine  they 
migrate  to  the  Malpighian  tubes  where  they  undergo  a  certain  degree  of 
development.  In  about  twelve  days  from  the  time  they  entered  the 
body  of  the  insect  they  pass  through  the  walls  of  the  Malpighian  tubes 
and  enter  the  mouth  parts.  If  the  piercing  organ  of  the  insect  is  broken 
during  the  act  of  sucking  blood,  the  animal  becomes  infected,  and  the 
larvse  are  carried  with  the  blood  or  l>anph  to  the  heart  where  they  attain 
sexual  maturity. 

Grassi  demonstrated  by  his  investigations  that  nearly  all  of  the  larvse 
of  the  filaria  of  man  die  in  the  intestines  of  mosquitoes,  and  that  the  dog 
filaria  cannot  live  in  other  parasitic  insects  harbored  by  dogs.  He  con- 
cluded, therefore,  that  the  larvse  from  affected  animals  reach  the  water 
directly. 

The  prevalence  of  the  disease  in  low  marshy  locahties  points  to  the 
transmission  of  hematic  filariasis  through  contaminated  water.  The 
larvse  from  affected  animals  may  reach  the  water  with  the  excrement,  the 
urine,  or,  occasionally,  with  blood  from  wounds.  In  such  case  infection 
may  be  direct  or  after  the  larvse  have  undergone  a  further  development 
in  an  intermediate  small  crustacean,  as  cyclops,  the  parasites  gaining 
entrance  to  the  mammalian  host  by  way  of  the  alimentary  canal  and 
from  here  reaching  the  blood  stream  to  be  carried  b}^  the  venous  blood 
to  the  right  heart. 

Treatment. — -Therapeutic  measures  in  this  form  of  filariasis,  espe- 
cially where  there  is  pronounced  disturbance  of  nutrition  and  circula- 
tion, is  unsatisfactory.  Nutritious  food  and  the  avoidance  of  exertion, 
conjoined  with  the  administration  of  heart  stimulants  and  prevention, 
so  far  as  possible,  of  reinfection,  may  bring  results  if  the  parasites  are 
not  too  numerous  or  the  disturbances  occasioned  by  them  are  not  too 
far  advanced. 

2.  Spiroptera  sanguinolenta  (Filaria  sanguinolenta) .  Filariidae 
(p.  244). — ^The  most  prominent  characteristic  of  this  worm  is  its  blood- 
red  color.  The  tail  of  the  male  is  obtuse,  spiral,  and  has  two  lateral 
wings.  There  are  two  spicules.  The  tail  of  the  female  is  obtuse  and 
slightly  curved.    The  vulva  is  situated  2  to  3  mm.  behind  the  mouth. 

Length  of  female,  6-8  cm.  (2  3/8-3  1/8  inches);  male,  3-5  cm.  (1  1/4- 
2  inches). 

The  eggs  are  thick-shelled,  elliptical,  and  about  30  microns  long  by 
12  microns  in  width. 

Occurrence  and  Pathogenesis. — This  nematode  of  the  dog  is  usually 
found  lodged  in  tumors  of  the  esophagus  and  stomach,  though  it  is 
occasionally  met  with  in  large  blood  vessels,  the  lungs,  and  in  lymph 
nodes.  The  tumors  varj^  in  size  from  that  of  a  hazel  nut  to  that  of  a 
pigeon's  egg,  and  usually  but  few  are  present.    They  lie  beneath  the 


FILARIID.E  251 

mucosa,  which  is  unaltered  with  the  exception  of  an  opening  at  the 
tumor's  sunnnit.    Outwardly,  they  are  limited  by  the  muscular  coat. 

Upon  incision  of  the  hardened  tissue  of  the  tumor  it  is  found  to  contain 
cavities  which,  on  pressure,  yield  a  purulent  fluid  with  which  are  ex- 
truded the  parasites.  A  varying  number  of  worms  may  be  found  coiled 
up  in  these  chambers,  generally  from  two  or  three  up  to  twenty. 

Symptoms  and  Course. — The  most  characteristic  symptom  of  the 
presence  of  this  worm  is  persistent  vomiting.  A  fatal  termination  may 
be  brought  about  from  inanition  resulting  from  the  repeated  vomiting, 
or  the  gastric  tumors  may  rupture  upon  the  peritoneum  and  cause  a 
fatal  peritonitis. 

Development. — Railliet  has  demonstrated  that  the  eggs  retain  their 
shells  in  their  passage  through  the  intestines  of  the  dog  and  reach  the 
outside  with  the  excrement.  Researches  of  Grassi  have  shown  that  the 
embryos  then  pass  into  the  body  of  a  cockroach,  probably'  by  its  feeding 
upon  the  egg-containing  excrement  of  infected  dogs.  In  the  bodj^-cavity 
of  this  insect  he  found  large  cysts  containing  larval  nematodes  agreeing 
in  color  with  this  species.  The  cysts  were  fed  to  dogs  which,  after  two 
weeks,  showed  on  necropsy  the  young  parasites  alread}^  embedded  in 
the  mucosa  of  the  esophagus.  Natural  infection  of  dogs  probably 
occurs  by  their  eating  the  roaches  containing  these  cj^sts. 

Treatment. — In  the  absence  of  precise  symptoms  indicating  the 
presence  of  these  worms,  the  diagnosis  in  practicalh'  all  cases  being  made 
post-mortem,  there  is  little  to  be  said  as  to  the  treatment  of  the  affec- 
tion. Bismuth  or  small  doses  of  cocaine  may  be  given  as  palliative 
treatment  for  the  relief  of  the  recurrent  vomiting, 

FlLARIID^    OF   THE    HoG 

1.  Arduenna  strongylina  (Spiroptera  strongylina).  Filariidae  (p. 
244). — The  body  is  subcylindrical  and  often  curved  ina  semicircle.  The 
anterior  portion  is  attenuated,  the  posterior  somewhat  broader.  The 
cuticle  is  densely  striated  transversely.  The  mouth  has  two  lateral 
lips,  each  with  three  lobes  leading  into  a  small  buccal  capsule  which  is 
followed  by  a  cylindrical  pharynx  marked  with  cuticular  ridges  forming  a 
series  of  spirals.  The  caudal  end  of  the  male  is  curved,  has  two  unequal 
wings,  and  five  pairs  of  stalked  papillae  asymmetrically  arranged.  The 
spicules  are  long  and  very  unequal.  The  vulva  of  the  female  is  slightly 
anterior  to  the  middle  of  the  body. 

Length  of  female,  16-22  mm.  (5/8-7/8  of  an  inch);  male,  10-15  mm. 
(3/8-5/8  of  an  inch). 

The  eggs  are  oval,  34-39  microns  long  by  20  microns  wide.  They 
have  thick  shells  and  contain  well-developed  embryos  at  the  time  of 
oviposition. 


252  PARASITES  OF  THE  DOMESTIC  ANIMALS 

The  species  is  parasitic  in  the  stomach  and  small  intestine  of  the  hog. 

2.  Physocephalus  sexalatus  (Spiroptera  sexalata).  Filariidie  (p. 
244). — The  body  is  subcylindrical  and  slightly'-  tapering  anteriorly.  The 
head  is  made  distinct  by  a  cuticular  inflation  extending  to  the  posterior 
end  of  the  pharynx.  The  mouth  has  two  three-lobed  lips,  each  lobe 
having  a  rounded  papilla  and  leading  into  a  small  buccal  capsule.  The 
cylindrical  pharynx  has  a  spiral  band  which  usually  breaks  up  into 
separate  rings  in  the  middle  of  its  course  and  again  becomes  spiral  toward 
the  posterior  end.  The  body  of  the  male  is  nearly  uniform  in  diameter. 
The  caudal  extremity  is  twisted  spirally  and  has  narrow  membranous 
wings  which  are  symmetrical.  There  are  eight  pairs  of  papillae,  of  which 
four  pairs  are  preanal  and  stalked,  the  postanal  papillae  small,  with 
short  stalks,  and  close  to  the  tail.  The  spicules  are  very  unequal.  The 
body  of  the  female  is  thickest  near  the  anus,  terminating  abruptly  in  a 
blunt  point  furnished  with  a  small  conical  tip.  The  vulva  is  posterior  to 
the  middle  of  the  body. 

Length  of  female,  13-19  mm.  (1/2-3/4  of  an  inch).  In  the  region  di- 
rectly anterior  to  the  anus  the  width  is  333-450  microns.  The  male  is 
6-9  mm.  (3/16-11/32  of  an  inch)  in  length. 

The  eggs  are  oval,  34  by  15  microns,  slightly  flattened  at  the  poles, 
and  thick-shelled.  They  contain  well-developed  embryos  at  the  time  of 
oviposition. 

The  species  is  parasitic  in  the  stomach  and  small  intestine  of  the  hog. 

In  neither  of  these  two  species  is  the  life  history  known.  The  thickness 
of  the  egg-shell  indicates  that  the  embryos  are  not  released  until  this  is 
acted  upon  by  the  gastric  juice  of  the  host,  and,  therefore,  that  develop- 
ment occurs  without  an  intermediate  host. 

In  a  report  upon  his  investigations  of  these  worms  published  in  1912, 
Foster,  of  the  Zoological  Division  of  the  Bureau  of  Animal  Industry, 
gives  the  following  summary: 

"Two  species  of  roundworms  belonging  to  the  family  Filariidae,  of 
particular  interest  to  helminthologists  and  veterinarians  on  account  of 
their  wide  distribution  and  frequency  of  occurrence  in  American  swine 
and  the  possibility  thai  they  may  cause  serious  injury  to  their  host,  are 
given  special  consideration  in  this  paper. 

"One  of  these  species,  identified  as  Spiroptera  strongylina,  has  re- 
cently been  placed  in  a  new  genus,  Arduenna,  of  which  it  is  the  type, 
and  several  errors  regarding  the  anatomy  of  this  parasite  have  been 
corrected.  Another  species,  Arduenna  dentata,  has  been  found  in  China 
associated  with  Arduenna  strongylina,  and,  although  not  yet  reported  in 
American  swine,  is  mentioned  in  this  connection,  as  further  investiga- 
tion may  reveal  its  presence  in  this  country. 

"Arduenna  strongylina  is  much  more  common  in  American  swine  than 
it  is  said  to  be  in  European  swine,  and  has  been  found  abundantly  in 


FILARIID.E  253 

the  slaughterhouses  of  St.  Louis,  Chicago,  South  Omaha,  and  Kansas 
City,  and  has  also  been  collected  at  Benning,  D.  C,  and  Bethesda,  Md. 

"Specimens  of  hogs'  stomachs  received  from  Chicago  showed  the 
worms  deeply  fastened  in  the  submucosa  or  embedded  in  necrotic  tissue 
near  which  were  deep  ulcers.  The  condition  suggested  infection  with 
Bacillus  necrophorus,  the  inoculation  with  which  might  easily  result  from 
the  burrowing  of  the  worms;  however,  owing  to  the  sterile  condition  of 
the  specimens  received,  this  could  not  be  satisfactorily  demonstrated. 
A  similar  diseased  condition  of  the  stomachs  of  hogs  in  Europe  is  attril)- 
uted  Iw  Von  Ratz  to  infection  with  Arduenna  strongylina.  Under  the 
circumstances  the  worm  should  be  regarded  with  grave  suspicion,  and 
general  prophylactic  measures  foi-  the  prevention  of  the  spread  of  the 
infection  are  suggested. 

"Commonl}^  associated  with  Arduenna  strongylina  in  this  country  is 
another  worm,  identified  as  Physocephalus  sexalatus,  first  described  by 
Molin  from  specimens  from  the  peccary  {Dicotyles  labiatus)  from  Brazil; 
also  found  by  him  associated  with  Arduenna  strongylina  from  the  wild 
boar  in  Germany.  It  is  also  reported  by  A'on  Listow  (who  apparentl>- 
mistook  this  species  for  Arduenna  strongylina)  and  Plana,  from  Europe, 
and  by  Railliet  and  Henry  from  Madagascar  and  Indo-China,  in  the 
former  case  associated  with  a  severe  gastritis.  Seurat  (1912)  has  re- 
cently reported  this  species  from  the  ass  and  dromedary  in  Algeria,  but 
his  statements  would  seem  to  I'equire  confirmation. 

"According  to  the  writers'  experience,  Physocephalus  sexalatus  is 
almost  as  widely  distributed  as  Arduenna  strongylina,  since  out  of  eight 
lots  of  specimens  of  the  latter  species,  specimens  of  Physocephalus  sexala- 
tus were  found  in  all  but  one.  In  a  mixed  infection,  however,  it  has 
never  been  found  as  abundantly  as  Arduenna  strongylina.  This  worm 
has  apparently  the  same  habit  of  injuring  the  mucosa  as  has  Arduenna 
strongylina,  as  both  species  were  found  in  the  same  necrotic  tissue  in  a 
hog's  stomach.  It  must  therefoi-e  be  considered  only  less  dangerous 
because  it  is  less  abundant,  and  should  be  subject  to  the  same  treatment 
suggested  for  infestation  with  Arduenna  strongylina.'" 

Control. — As  that  part  of  the  parasite's  life  history  external  to  the 
host  is  not  known,  no  more  than  general  preventive  measures  can  be 
recommended.    The  author  quoted  above  suggests  the  following: 

"1.  Hogs  suffering  from  loss  of  appetite  oi-  failing  to  fatten  undei- 
proper  food  and  hygiene  should  be  examined  for  evidence  of  infection  b>- 
killing  one  or  two  and  looking  in  the  stomach  for  worms;  or,  where 
practicable,  the  feces  of  the  entire  herd  may  be  examined  microscopically. 

"2.  Those  swine  found  infested  with  stomach  worms  should  be 
isolated  from  noninfected  or  presumably  noninfected  swine  in  clean 
pens,  and  the  dung  removed  daily  and  mixed  with  quicklime  or  dis- 
posed of  by  carting  it  to  places  to  which  hogs  do  not  have  access. 


254  PARASITES  OF  THE  DOMESTIC  ANIMALS 

"3.  The  noninfected  swine  should  not  be  allowed  to  remain  in  the 
same  pens  formerly  occupied  by  the  infested  animals,  but  should  have 
clean  quarters.  The  old  pens  should  be  thoroughly  disinfected  with  lune 
after  removing  the  clung  and  burning  over  the  ground  where  feasible." 

Treatment. — Treatment  in  such  infection  is  mainly  prophylactic. 
As  a  medicinal  remedy,  probably  benzine  is  one  of  the  best.  It  may  be 
given  in  two  to  four  dram  doses  in  milk,  administered  as  recommended  in 
the  treatment  for  ascarids.  Areca  nut,  one  grain  per  pound  of  body- 
weight,  may  be  given  in  the  same  manner. 

FiLARiiD^  OF  Chickens 

Of  the  filariae  harbored  by  poultry,  four  species  may  be  mentioned 
here.    As  to  the  first  three  at  least,  there  is  little  of  record  in  this  country. 

1.  Dispharagus  spiralis.  Filariidse  (p.  244). — The  body  is  generally 
rolled  spirally.  There  are  three  papillse  around  the  mouth.  The  tail 
of  the  male  is  spiral  and  is  provided  with  wings.  There  is  but  one 
spicule.  The  female  is  9  mm.  (3/8  of  an  inch)  and  the  male  is  7  nun. 
(5/16  of  an  inch)  in  length. 

This  species  lives  in  the  wall  of  the  esophagus  and  intestines  of  poultry. 

2.  Dispharagus  hamulosus.  Filariid®  (p.  244). — The  body  has 
eight  denticulated  longitudinal  wings.  The  female  is  16-25  mm.  (5/8- 
1  inch)  and  the  male  is  14  mm.  (9/16  of  an  inch)  in  length. 

This  worm  has  been  found  in  Brazil  and  in  Italy.  It  is  parasitic  in 
the  gizzard  of  fowls. 

3.  Dispharagus  nasutus.  Filariida?  (p.  244).— The  body  is  slightly 
attenuated  at  its  extremities.  There  are  two  long  terminal  papillse 
on  each  side  of  the  mouth,  from  which  two  fiexuous  wings  have  their 
beginning.  These  pass  to  a  distance  of  0.6  mm.,  then  curve  forward. 
The  male  is  filiform,  with  caudal  extremity  spiral.  There  are  two 
unequal  spicules.  The  vulva  of  the  female  is  in  the  anterior  portion  of 
the  body.  The  female  is  5-9  mm.  (3/16-3/8  of  an  inch)  and  the  male 
is  5  mm.  in  length. 

It  inhabits  the  gizzard  of  fowls. 

4.  Tetrameres  fissispina  (Tropisurus  fissispinus).  Filariidse  (p.  244). 
— This  species  is  characterized  by  a  marked  sexual  dmiorphism.  The 
male  is  white,  slender,  3-6  mm.  (1/8-1/4  of  an  inch)  in  length,  and  bears 
upon  the  median  and  lateral  hues  spines  forming  four  longitudinal  series. 
The  body  of  the  female  is  subglobular,  2  mm.  in  length  by  1-2  mm.  (in 
width;  reddish  in  color;  tail  short  and  conical. 

The  species  is  found  in  the  proventriculus  of  the  domestic  duck  where 
it  inhabits  submucous  cysts  and  may  set  up  a  serious  inflammation  of 
these  parts.  It  is  said  to  be  quite  common  in  parts  of  New  York  State, 
and  it  is  probable  that  it  exists  in  other  localities. 


chapter  xxi 

xe:\iatoda.    fa:mily  v.    stroxgylid.e.    subfa:\iily  i. 
:^ietastroxgylix.e 

AVORMS    OF   THE    RESPIRATORY    TrACT 

Xematoda  (p.  217). — The  most  prominent  character  by  which  this 
family  may  be  recognized  is  the  caudal  bursa  of  the  male  which  is  usually 
well  developed.  The  body  is  elongate,  cylindrical,  and  in  some  cases 
filiform.  A  buccal  capsule  may  be  present  or  absent  and  ma}'  be  armed 
with  teeth  in  its  interior.  The  esophagus  is  more  or  less  enlarged  poste- 
riorly. The  males  have  a  more  or  less  well-developed  caudal  bursa, 
usually  divided  into  lateral  lobes,  each  supported  by  ra^'-like  chitinous 
thickenings.  There  are  two  equal  or  unequal  spicules.  The  \ailva  of  the 
female  may  be  posterior  or  anterior  to  the  middle  of  the  body,  usually 
posterior,  in  some  cases  near  the  anus. 

Parasitism. — While  these  worms  in  their  adult  form  mostly  infest 
the  lumen  of  the  alimentar}-  and  respiratory  tracts,  other  organs  may  be 
primarily  or  secondarily-  involved.  The  subserous  larval  phase  of  in- 
testinal invasion  b}-  the  genus  (Esophagostomum  and  the  vascular 
larvae  of  Strongylus  vulgaiis  may  be  mentioned  in  this  connection,  while 
other  organs  are  not  uncommonly  invaded  by  migration.  The  term 
strongylosis  is  a  general  one  which  has  been  applied  to  any  helminthiasis 
produced  by  strongyles.  It  is  more  precisely  used  when  qualified  by 
terms  indicating  the  seat  of  invasion,  as  gastric,  intestinal,  bronchial, 
vascular,  or  renal  strongylosis. 

Being  responsible  for  some  of  the  most  depletive  and  fatal  forms  of 
parasitism,  the  strongyl  worms  have  especially  demanded  study  and 
investigation;  this  has  established  important  advances  in  knowledge 
as  to  their  pathogenicity,  though  much  remains  to  be  revealed  as  to 
their  life  histories  and  consequently  as  to  effectual  means  for  their 
control.  In  general  it  may  be  said  that  low  marshy  pasturage  and  wet 
seasons  favor  infestation  with  strongyles,  which  would  indicate  that  the 
ova  and  embr^-os  of  some  forms  at  least  are  spread  by  water,  and  that 
contaminated  water  and  herbage  are  the  vehicles  by  which  the  parasites 
reach  their  hosts. 

As  in  other  parasitic  invasions,  age  and  physical  condition  have  a 
decided  influence  in  predisposition  to  strongylosis.  Young  ruminating 
animals  are  especially  susceptible  to  the  broncho-pulmonary  form, 
while  in  all  animals  which  mav  be  affected  both  vouth  and  senilitv  favor 


256  PARASITES  OF  THE  DOMESTIC  ANIMALS 

intestinal  infestation.  Again,  the  general  rule  applies  that  resistance  is 
always  reduced  in  animals  in  low  physical  condition,  while,  essentially, 
crowding  and  general  unsanitary  conditions  favor  the  transmission  and 
spread  of  the  parasites. 

Of  the   Strongylidae  three   subfamilies  may  be   distinguished,   viz: 

Subfamily      I.  Metastrongylince. 

Subfamily    II.    Trichostrongylinae. 

Subfamily  III.  Strongylinae. 

Subfamily  I.  Metastrongylix^ 

Strongy-lidse  (p.  255). — This  subgroup  comprises  the  strongyles 
parasitic  in  the  respiratory  system  and  some  in  the  circulatory  system. 
The  buccal  capsule  is  absent  or  very  slightly  developed.  The  bursa  of 
the  male  is  frequently  atypical  in  structure  and  number  of  rays.  There 
are  two  equal  spicules.  The  eggs  are  in  varying  stages  of  development 
when  deposited. 

The  life  history  is  as  yet  unknown.  It  is  probable  that  infection  is 
without  intermediate  host.  Romanovitch  and  Slavine  (1914)  found 
that  eggs  of  Didyocaulus  filaria  when  placed  in  water  formed  embryos. 
Two  moltings  followed,  the  cuticle  being  retained  and  encapsulating  the 
larvae,  and  these  when  fed  to  sheep  produced  infection  with  the  adult 
worms.  This  would  indicate  direct  development  and  infection  by  the 
worms  of  this  group. 

Bronchial  and  Pulmonary  Strongylosis  of  the  Sheep  and  Goat 

Three  species  of  Metastrongylinse  invade  the  respiratory  tract  of  the 
sheep  and  goat;  a  fourth, — Metastrongylus  apri — described  under 
broncho-pneumonia  of  the  hog,  is  exceptionally  found  in  the  sheep. 

1.  Dictyocaulus  filaria  (Strongylus  filaria).  Fig.  130.  Meta- 
strongylina?  (p.  256). — The  body  is  white,  filiform,  slightly  tapering  at 
posterior  extremity.  The  anterior  extremity  is  obtuse,  without  wings; 
mouth  circular  and  without  papillae.  The  bursa  of  the  male  is  notched 
in  front;  spicules  short,  thick,  brown  in  color,  and  provided  with  mem- 
branous wings.  The  caudal  extremity  of  the  female  is  straight  and 
conical;  vulva  somewhat  posterior  to  the  middle  of  the  body. 

Length  of  female,  5-10  cm.  (2-4  inches);  male,  3-8  cm.  (1  1/8-3  1/8 
inches). 

The  eggs  are  oval,  112-135  microns  in  length  by  52-67  microns  in 
breadth.  They  contain  developed  embryos  which  are  liberated  in  the 
bronchi  as  the  eggs  are  deposited. 

The  embryos  are  540  microns  long  ]:)y  20  microns  in  diameter,  tapering 
to  a  blunt  point  behind. 


:\IETASTRONGYLIX.E  ^.57 

The  worm  is  parasitic  in  the  respiratory  organs  of  the  sheep,  goat, 
camel,  and  deer. 

2.  Synthetocaulus  rufescens  (Strongylus  rufescens).  Fig.  131. 
INIetastrongyHnse  (p.  256).— The  body  is  thin  and  hair-hke,  brownish 
red  in  color.  The  mouth  has  three  papilliform  lips.  The  bursa  of  the 
male  is  notched  in  front  and  has  two  small  lateral  indentations.  The 
spicules  are  striped  transversely  and  rounded  at  their  ends.  The  poste- 
rior extremity  of  the  female  terminates  in  a  blunt  point;  vulva  imme- 
diately in  front  of  the  anus  at  the  base  of  a  small  pre-anal  elevation. 


B 


Fig.  130. — Dictyocaulus    filaria:    a,    female;    b,    male, 
natural  size;  c,  anterior  extremitj-;  d,  eggs, — enlarged. 

Length  of  female,  25-35  nun.  (5/8-1  3/8  inches) ;  male,  18-28  mm. 
(3/4-1  1/2  inches). 

The  eggs  are  oval,  75-120  microns  in  length  by  45-82  microns  in 
breadth.  Segmentation  has  advanced  at  the  time  they  are  deposited, 
after  which  the  embryos  develop  rapidly  and  are  liberated  in  the  pul- 
monary alveoli.  From  the  alveoli  the}'  pass  to  the  bronchi  and  trachea 
from  whence  they  are  expelled  to  the  outside  where  they  have  a  strong 
vitalitj'  and  are  capable  of  resisting  desiccation  for  a  long  time. 

As  found  in  the  trachea  and  larger  bronchi,  the  embryos  measure 
300-400  microns  in  length  by  16-18  microns  in  breadth. 

The  worm  is  parasitic  in  the  respiratory  organs  of  the  sheep,  goat,  and 
rabbit. 


258  PARASITES  OF  THE  DOMESTIC  ANIMALS 

3.  Synthetocaulus  capillaris  (Strongylus  capillaris).  Metastrongy- 
linse  (p.  256). — This  worm  like  the  preceding  is  thin  and  brownish  in 
color.  The  mouth  has  six  papillae  and  the  caudal  extremity  is  pointed. 
The  caudal  extremity  of  the  male  is  curled  spirally;  bursa  small  and  sup- 
ported by  seven  ribs;  spicules  dentate.  The  vulva  of  the  female  is  just 
in  front  of  the  anus. 

Length  of  female,  20-22  mm.  (7/8  of  an  inch);  male,  14  mm.  (9/16  of 
an  inch). 

The  eggs  are  brownish  in  color.  The  embryos  develop  after  the  eggs 
are  deposited  and  are  liberated  in  the  pulmonary  alveoli  and  bronchi. 
After  depositing  the  eggs  the  adult  worms  invade  the  lung  tissue  where 
they  die  and  become  encapsulated. 

The  worm  is  parasitic  in  the  respiratory  organs  of  the  sheep  and  goat. 

Bronchial  and  pulmonarj-  strongylosis  of  sheep  and  goats  is  due  to 
the  presence  of  these  worms  together  with  their  eggs  and  larva)  in  the 
air  passages  and  alveoli.  The  affection  is  usually  a  broncho-pneumonia, 
though  the  S3anptoms  presented  will  be  somewhat  subordinate  to  the 
infecting  species.  If  the  infection  is  with  Dictyocaulus  filaria,  or  this 
dominates  a  pulmonary  species  coexisting  in  the  same  animal,  the 
bronchial  si-niptoms  will  be  the  more  prominent.  On  the  other  hand, 
in  an  abundant  infestation  with  Synthetocaulus  rufescens  the  pulmonary 
symptoms  are  likely  to  predominate. 

Symptoms. — Bronchial  strongylosis  of  sheep  and  goats  is  usually 
due  to  the  presence  of  adults  of  the  species  Dictyocaulus  filaria  in  the 
larger  air  passages,  and  in  most  all  cases  the  pulmonarj^  form  is  asso- 
ciated with  it.  In  general,  the  symptoms  are  those  of  a  bronchial 
catarrh.  There  is  a  short  dry  cough  which  at  first  is  at  long  intervals. 
Later  this  is  more  frequent  and  may  become  paroxysmal  and  accom- 
panied by  distressing  attacks  of  dyspnoea.  The  bronchial  secretion 
expelled  through  the  mouth  and  nostrils  is  frequenth^  lumpy  and  usually, 
though  not  always,  contains  the  worms  with  their  eggs  and  embryos, 
the  latter  found  by  examination  of  the  material  with  the  microscope. 
At  first  the  liveliness  and  appetite  of  the  animal  are  retained  and  there 
is  no  appreciable  loss  of  flesh.  If  the  number  of  the  parasites  remains 
small  there  will  continue  to  be  little  or  no  manifestation  of  their  presence. 
Relative  to  the  degree  of  infestation,  the  symptoms  may  pass  through 
the  gradations  above  given  to  extreme  difficulty  in  respiration,  emacia- 
tion, pallor,  and  edema  of  the  larynx,  muzzle,  and  ej^elids,  the  brisket 
and  other  dependent  parts  of  the  body  in  some  cases  also  becoming 
edematous.  Finally,  in  extreme  weakness,  the  animal  is  unable  to  get 
upon  its  feet  and,  in  a  condition  of  complete  prostration,  succumbs. 

Symptoms  occasioned  by  the  presence  of  strongyles  in  the  pulmonary 
air  spaces  and  alveoli  are  in  themselves  less  prominent  than  those  of 
verminous  bronchitis.    Attentive  percussion  over  the  thorax  may  reveal 


METASTROXGYLIN.E  259 

dullness  in  circumscribed  areas,  but  as  a  rule  it  shows  nothing  abnormal. 
Usually  symptoms  are  only  observed  upon  the  appearance  of  cachexia 
and  weakness  following  the  development  of  punalent  areas  in  the  lung 
tissue,  this  finally  bringing  about  the  death  of  the  anmial. 

Course  and  Prognosis. — The  duration  of  broncho-pulmonarj^  stron- 
g3'losis  varies  according  to  the  number  of  parasites  present  and  the 
toleration  of  the  affected  anmial.  In  the  majority  of  unfavorable  cases 
the  disease  will  run  a  course  of  two,  three,  or  four  months.  In  the  very 
young  this  period  may  be  much  shortened,  the  animal  succumbing  in  a 
few  days  from  the  first  observation  of  sj-mptoms.  Strong  adult  animals, 
on  the  other  hand,  are  likely,  unless  there  is  reinfection,  to  gradually 
recover  during  a  course  of  six  to  eight  months.  In  any  case  where  the 
symptoms  are  well  marked  a  fatal  termination  is  to  be  looked  for. 

For  Post-mortem  Appearance,  Development  and  Etiology,  Control, 
and  Treatment,  refer  to  pp.  262-265. 

Bronchial  axd  Pulmonary  Strongylosis  op  Cattle 

Dictyocaulus  viviparous  (Strongylus  micrurus).  Fig.  132.  ^Nleta- 
strong3'hna3  (p.  256). — The  body  is  long,  slender,  and  attenuated  at  both 
extremities.  The  head  is  rounded  and  without  wings; 
mouth  circular  and  nude.  The  bursa  of  the  male  is 
small,  without  lobes,  and  is  supported  by  five  ribs. 
There  are  two  short  and  strong  spicules.  The  tail  of 
the  female  terminates  in  a  sharp  point;  vulva  near  the 
posterior  sixth  of  the  body. 

Length  of  female,  6-8  cm.  (2  3/8-3  1/8  inches); 
male,  3.5-i  cm.  (1  3/8-1  5/8  inches). 

The  eggs  are  oval,  85  microns  in  length  by  35  mi- 
crons in  breadth.  Embryos  are  developed  within  the 
body  of  the  female  and  are  liberated  at  the  time  the 
eggs  are  deposited. 

The  liberated  embiyos  are  256  microns  long  by  25 
microns  in  thickness.  The}^  pass  from  the  bronchi 
to  the  trachea  from  which  they  are  expelled  to  the 
exterior. 

Symptoms. — In  light  infestations  no  symptoms 
may  be  observed  save  an  occasional   cough.    When  iQo_n- 

the  parasites  are  more  numerous  the  cough  becomes  tyocaulus  ' Vi-v-ipar- 
more  frequent  and  sonorous,  and,  in  the  further  course,  ous;  male  at  right, 
paroxysmal,  the  animal  extending  the  head,  protmding  urTri^se^*  ^^^*'  °^*' 
the  tongue,  and  freely  sahvating  during  the  attacks. 
The  paroxysms  are  accompanied  by  dj'spnoea  and  suffocation,  with 
beating  flanks,  quickened  pulse,  and  injected  conjunctiva.     In  severe 


260  PARASITES  OF  THE  DOMESTIC  ANIMALS 

cases  with  violent  attacks  occurring  several  times  a  day,  the  gasping 
animal  may  fall  prostrated  and  die  from  asphyxiation. 

The  mucus  expelled  by  the  coughing  is  frequently  streaked  with 
blood  and  contains  the  worms  which  are  often  collected  in  masses.  It 
is  to  these  masses  obstructing  the  large  bronchi  that  the  suffocation  is 
due. 

Course  and  Prognosis. — What  has  been  said  as  to  influences  gov- 
erning the  duration  and  intensity  of  the  malady  in  sheep  will,  in  general, 
apply  to  cattle  also.  The  prognosis,  especially  in  calves,  is  usually 
unfavorable.  Death  is  generally  brought  about  in  three  to  six  months 
by  asphj^xia  or  extreme  cachexia  and  exhaustion. 

For  Post-mortem  Appearance,  Development  and  Etiolog}^,  Control, 
and  Treatment,  refer  to  pp.  262-265. 

Bronchial  and  Pulmonary  Strongylosis  of  the  Pig 

Two  strongyles  are  met  with  in  the  respiratory  tract  of  the  hog. 

1.  Metastrongylus  apri  (Strongylusapri;  St.  paradoxus).    Fig.  133. 

Metastrongylinse  (p.  256).— The  body  is  white  or  brown.  The  mouth 
has  six  hps.  The  bursa  of  the  male  is  bilobate,  each  lobe 
sustained  by  five  ribs.  The  spicules  are  slender  and  very 
long,  measuring  about  4  mm.  (3/16  of  an  inch)  and  each 
terminated  in  a  barb.  The  tail  of  the  female  terminates 
b}^  a  short  hook-like  process.  The  vulva  is  on  a  slight 
eminence  immediately  in  front  of  the  anus. 

Length  of  female,  2-5  cm.  (3/4-2  inches);  male,  1.2-2 
cm.  (1/2-3/4  of  an  inch). 

The  eggs  are  oval,  57-100  microns  in  length  by  39-72 
microns  in  breadth.  They  contain  developed  embryos  at 
the  time  they  are  deposited  and  these  are  liberated  in 

M?tastron'^us    *^^®  bronchi. 

apri;    male     at       The  embryos  at  the  time  of  their  liberation  measure 
right,  female  at  220-250  microns  in  length  and  10-12  microiis  in  thickness. 
left,  — natural       rpj^^  worm  is  parasitic  in  the  respiratory  tract  of  do- 
mestic and  wild  hogs,  occasionally  of  sheep. 

2.  Metastrongylus  brevivaginatus.  Metastrongylina3  (p.  256). — 
This  species  has  for  a  long  time  been  confounded  with  the  preceding 
under  the  name  of  Strongijlus  paradoxus.  It  differs  from  it  in  the  shape 
of  the  bursa  and  in  the  spicules  which  are  short,  each  terminating  in 
two  barbs. 

The  worm  is  parasitic  in  the  respiratory  tract  of  domestic  hogs. 

Occurrence  and  Symptoms. — While  the  presence  of  strongyles  in 
the  bronchi  of  pigs  has  been  known  for  a  long  time,  it  is  not  as  frequently 
observed  in  these  animals  as  in  sheep  and  calves.    Heav}'-  infestations 


METASTRONGYLIX.E  261 

with  Metastrongylus  apri  sonietinies  occur  with  high  mortaHt}^  among 
pigs.  Such  cases  take  a  course  similar  to  that  in  sheep  and  calves.  In 
the  milder  cases  there  ma}-  be  disturbances  of  nutrition  and  occasional 
cough,  though  usually  in  light  invasions  nothing  is  observed  to  cause 
suspicion  of  the  presence  of  the  worms  which  are  onlv  revealed  on 
examination  of  the  respiratory  passages  after  slaughtering. 

For  Post-mortem  Appearance,  Development  and  Etiology,  Control, 
and  Treatment,  refer  to  pp.  262-265. 

Broxchial  axd  Pulmoxary  Stroxgylosis  of  the  Horse 

Dictyocaulus  arnfieldi  (Strongylus  arnfieldi). — ^Metastrongj'linse 
(p.  256). — The  body  is  white  and  filiform  and  the  mouth  is  nude.  The 
bursa  of  the  male  is  short,  with  faint  lobulation.  The  spicules  are 
slightly  arched,  200-240  microns  in  length,  and  have  a  net-like  marking. 
The  tail  of  the  female  is  short,  slightly  curved,  and  terminates  in  a 
blunt  point.  The  \T.ilva  is  situated  somewhat  posterior  to  the  middle 
of  the  body  and  is  not  prominent. 

Length  of  female,  4.3-5.51  cm.  (1  11/16-2  3/16  inches);  male.  2.8- 
3.6  cm.  (1  1/8-1  7/16  inches). 

The  eggs  are  oval  and  measure  80-100  microns  in  length  l)y  50-60 
microns  in  breadth.  The}-  contain  developed  embryos  at  the  time  they 
are  deposited,  and  these  are  liberated  in  the  respiratory  passages  of  the 
host. 

The  liberated  embryos  measure  400—490  microns  in  length  and  have 
a  thickness  of  14-18  microns. 

The  worm  is  parasitic  in  the  bronchi  of  the  horse  and  ass. 

Bronchial  strongylosis  of  equines  seldom  occurs.  Clinically  it  is 
manifested  by  symptoms  similar  to  those  of  verminous  bronchitis  in 
other  animals. 

For  Post-mortem  Appearance,  Development  and  Etiology,  Control, 
and  Treatment,  refer  to  pp.  262-265. 

Cardio-Pulmoxary  Stroxgylosis  of  the  Dog 

Haemostrongylus  vasorum  (Strongylus  vasorum).  ^letastron- 
gylinie  (p.  256). — The  body  is  filiform,  whitish  or  reddish  in  color,  and 
has  longitudinal  striations.  The  mouth  is  nude.  The  bursa  of  the  male 
has  two  lobes,  each  sustained  by  four  ribs.  The  vulva  of  the  female 
is  situated  in  front  of  the  anus. 

Length  of  female,  18-21  nun.  (3,4-13/16  of  an  inch);  male,  14-18  nun. 
(9yl6-3/4of  aninch). 

The  eggs  are  oval  and  measure  70-80  microns  in  length  by  40-50 
microns  in  breadth.    Segmentation  occurs  after  they  are  deposited. 


262  PARASITES  OF  THE  DOMESTIC  ANIMALS 

When  freed  from  the  eggs  the  embiyos  measure  300-360  microns  in 
length  by  13  microns  in  thickness. 

The  worm  Hves  in  the  right  heart  and  ramifications  of  the  piihnonary 
artery  of  the  dog. 

Cardio-puhiionary  strongylosis  of  the  dog  is  due  to  the  presence  of 
these  parasites,  together  with  their  eggs  and  embryos,  in  the  right 
ventricle  of  the  heart  and  small  ramifications  of  the  pulmonary 
artery. 

Symptoms. — Symptoms  in  this  form  of  strongylosis  of  the  dog  are 
obscure,  and  generally  the  disease  is  not  recognized  until  post-mortem 
examination  of  the  animal.  Respiratory  disturbances  occur  in  some 
cases,  and  there  may  be  the  development  of  ascites.  The  attacks  of 
respiratory  difficulty  may  disappear  after  a  few  days,  or  the}^  may  lead 
to  asphyxia  and  the  death  of  the  animal. 

For  Post-mortem  appearance,  refer  to  page  263. 

Pulmonary  Strongylosis  of  the  Cat 

Synthetocaulus  abstrusus  (Strongylus  pusillus).  Metastrongylinse 
(p.  256). — The  body  is  filiform  and  the  mouth  is  without  papillae.  The 
bursa  of  the  male  is  short  and  slightly  festooned.  The  spicules  are  slen- 
der, long  and  recurved.  The  caudal  extremity  of  the  female  terminates 
in  a  blunt  point;  vulva  immediately  in  front  of  the  anus. 

Length  of  female,  about  10  mm.  (3/8  of  an  inch);  male  about  5  mm. 
(3/16  of  an  inch). 

The  eggs  are  oval  or  subglobular,  60-85  microns  in  length  by  35-80 
microns  in  breadth.    Segmentation  occurs  after  they  are  deposited.    . 

The  liberated  embryos  are  370^50  microns  in  length  by  16-18 
microns  in  diameter. 

The  worm  is  parasitic  in  the  lungs  of  the  cat. 

Symptoms. — Verminous  pneumonia  of  cats  produced  by  the  ova  and 
embryos  of  this  worm  not  infequently  occurs  without  symptoms  by 
which  it  may  be  recognized.  On  the  other  hand,  the  animals  may  have 
a  frequent  cough  accompanied  by  vomiting.  Where  emaciation  and 
diarrhea  follow  upon  such  symptoms,  death  will  usually  result  after  a 
course  of  two  to  three  months. 

Post-Mortem  Appearance  in  Bronchial  and  Pulmonary 
Strongylosis 

Animals  which  have  died  as  a  result  of  strongyles  in  the  respirator}^ 
passages  will,  upon  necropsy,  show  an  abundant  collection  of  mucoid 
and  mucopurulent  material  in  the  bronchial  tubes  which  is  frequently 
streaked  with  blood  and  contains  the  adult  worms,  ova,  and  embryos. 


:\IETASTRONGYLIN.E  263 

The  worms  may  be  in  masses  sufficient  to  obstruct  the  medium-sized 
or  larger  bronchi  which  in  places  may  present  sac-like  dilations  con- 
taining bundles  of  worms  together  with  more  or  less  purulent  mucus. 
The  mucosa  of  the  heavil}-  infested  bronchi  is  edematous  and  may  show 
hemorrhagic  streaks.  In  the  vicinity  of  bronchial  dilations  especially 
there  is  proliferation  of  connective  tissue,  the  air-containing  tissue 
being  compressed  and  obliterated  and  at  the  periphery  sometimes 
showing  localized  pleuritic  adhesions. 

In  pneumonia  due  to  the  presence  of  strongyles  three  forms  have 
been  distinguished,  viz:  1.  A  lobar  pneumonia  due  to  the  presence  of 
the  adult  worms  in  the  ramifications  of  the  bronchi.  2.  A  diffuse  pneu- 
monia due  to  ova  and  embryos  which  invade  the  pulmonary  tissue  in 
large  numbers.  3.  A  nodular  or  pseudo-tuberculous  pneumonia  due 
to  the  accumulation  of  eggs  and  embryos  in  circumscribed  parts  of  the 
lungs.  The  last  is  the  most  common  form  and  is  characterized  by  the 
presence  of  small,  hard,  grajdsh  yellow  centers  from  the  size  of  a  millet 
seed  to  that  of  a  pea  which  may  be  more  or  less  confluent.  Most  of 
these  nodules  are  found  toward  the  periphery  of  the  lungs,  particularl}^ 
at  the  margins  and  just  beneath  the  pleura.  Generally  they  adhere 
closely  to  the  surrounding  tissue,  var^'ing  in  color  from  yellow,  grayish 
yellow,  reddish  brown,  violet,  or  black  according  to  their  age  and  the 
character  of  the  inflammatory  process.  All  of  the  centers  become  caseous 
and  finally  undergo  calcareous  infiltration. 

In  addition  to  the  bronchial  and  pulmonary  lesions  there  are  presented 
in  severe  cases  the  evidences  characteristic  of  ansemia  and  cachexia, 
involving  subcutaneous  edema  and  serous  exudate  in  the  cavities  of  the 
body. 

Dogs  which  have  suffered  from  cardio-pulmonary  strongjdosis  will, 
on  necrops3%  reveal  adult  worms  {Hcemostromjylus  vasorum)  in  the  right 
heart  and  branches  of  the  pulmonary  artery.  The  lungs  at  the  bases  of 
their  lobes  show  circumscribed  granular  areas  in  which  the  tissue  is 
gra\',  compact,  and  heavier  than  water.  The  granules  are  hardly  the 
size  of  a  pin's  head,  semi-transparent,  and  give  a  roughened  aspect  to 
the  surface.  About  the  eggs  and  embryos  lodged  in  the  small  arterioles 
there  are  found  small  pseudo-follicles  which,  on  histological  examina- 
tion, will  exhibit  three  zones, — (1)  a  central  consisting  of  a  giant  cell 
containing  a  segmented  egg  or  embryo;  (2)  a  middle  of  epithelial  cells; 
and  (3)  a  peripheral  consisting  of  embryonal  tissue  elements  disposed 
circularly.  Larger  nodules  may  be  found,  usually  in  close  relationship 
to  a  clot  in  a  branch  of  the  pulmonary  artery  in  the  vicinity  of  which 
there  is  an  accumulation  of  adult  strongyles. 

Development  and  Etiology. — The  lungworms  deposit  their  eggs  in 
the  respiratory  passages  of  their  host  and  the  freed  embr^'os  are  either 
expelled  directly  with  the  bronchial  secretion  or,  passing  to  the  pharynx, 


264  PARASITES  OF  THE  DOMESTIC  ANIMALS 

are  swallowed  and  reach  the  outside  with  the  feces.  Further  than  this 
little  is  known  as  to  their  life  history.  The  larvae  do  not  appear  to  pass 
through  any  stages  of  development  in  the  bronchi  of  their  host,  the  first 
phases  of  their  existence  probably  requiring  that  they  be  expelled  from 
the  animal. 

Having  reached  the  outside,  if  the  larvae  encounter  sufficient  warmth 
and  moisture,  they  molt  and  this  is  later  followed  by  a  second  molting 
after  which  they  retain  their  coverings  and  in  this  condition  may  resist 
desiccation  for  a  long  thne.  It  is  probable  that  the  larvae  find  their 
way  to  a  host  with  the  wet  grass  and,  especially  in  the  case  of  sheep, 
with  collections  of  water  upon  the  pastures  which  the  animals  drink. 
The  view  as  to  direct  development  and  infection  is  supported  by  the 
investigations  of  Romanovitch  and  Slavine  (p.  256),  and  it  seems 
probable  that  in  all  cases  of  bronchial  and  pulmonary  strongylosis  the 
infection  is  direct.  Some  authors,  however  (Cobbold,  Leuckart),  be- 
lieve that  a  portion  of  the  larval  stage  is  lived  in  an  invertebrate  host,  as 
an  earthworm,  larval  insect,  or  mollusc. 

The  larvae  are  usually  taken  up  by  the  host  animals  in  the  spring, 
though  it  is  probable  that  infection  may  occur  at  any  time  during  the 
pasture  season."  That  infection  cannot  occur  directly  from  animal  to 
animal  has  been  demonstrated  by  Leuckart,  Herms  and  Freeborn  and 
others  who  were  not  successful  in  bringing  it  about  l^y  the  introduction 
into  the  respirator3^  passages  and  stomach  of  bronchial  mucus  containing 
numerous  embryos. 

The  course  of  the  larval  worms  in  reaching  the  l^ronchi  after  natural 
infection  by  way  of  the  digestive  organs  has  not  been  demonstrated. 
Based  upon  the  function  of  rumination  and  the  peculiar  susceptibility 
of  ruminating  animals,  the  invasion  of  the  air  passages  has  been  attrib- 
uted to  the  regurgitation  of  contaminated  food,  the  worms  passing 
from  the  pharynx  to  the  larynx  and  trachea.  But  this  hypothesis  seems 
to  have  no  more  than  plausibility  in  its  support,  and  certainly  cannot 
well  apply  to  the  case  of  the  non-ruminating  hog. 

Control. — In  districts  where  bronchial  and  pulmonary  strongylosis 
prevails,  low,  marshy  and  wet  pastures  or  parts  of  pastures  should  not 
be  accessible  to  susceptible  animals.  Drainage  and  a  liberal  covering 
of  the  ground  with  lime  phosphates  will  do  much  to  destroy  the  larvae. 
Bearing  in  mind  that  young  animals  are  more  susceptible  to  attack  than 
older  ones,  it  is  advisable  where  the  disease  prevails  to  give  them  feed 
and  water  each  day  before  they  are  turned  upon  pasture.  This  will  in  a 
measure  prevent  them  from  going  to  pools  and  marshy  places  for  water 
where  they  are  likely  to  linger  and  graze  unless  their  night's  fast  has 
been  previously  somewhat  broken.  Where  hogs  and  cattle  are  con- 
cerned the  pens,  stables  and  drinking  places  should  be  repeatedly  cleaned 
and  disinfected.     Sputum,  feces   and  bedding  are  not   to   be  placed 


METASTRONGYLIN.E  265 

with  manure  to  be  spread  upon  the  fields,  but  should  be  collected  and 
burned  as  should  also  the  infected  respirator}?-  organs  of  slaughtered 
animals. 

Treatment. — ^Treatment  with  a  view  to  attacking  the  worms  by  way 
of  the  digestive  tract  with  remedies  supposed  to  act  by  their  excretion 
through  the  lungs  can  at  most  be  but  mildly  successful.  Administered 
in  this  way,  a  sufficient  quantity  of  the  anthelmintic  to  be  effectual  would 
probably  include  the  host  in  its  destructive  effect. 

Fumigation  with  various  substances  has  been  recommended  and 
widely  practiced.  This  procedure  has  more  to  reconnnend  it  than  the 
first  mentioned  in  that  the  remedy  reaches  the  worms  directly,  having 
such  a  deleterious  action  upon  them  that  the}'  are  more  readity  expelled 
in  the  coughing  induced  by  the  irritant  smoke  and  vapors.  Again  an 
objection  to  the  method  is  the  intensity  of  application  required  for  its 
success,  this  demanding  that  the  animals  be  subjected  to  the  fumes  until 
they  are  dangerously  close  to  asphyxiation. 

AVhere  the  fumigation  treatment  is  resorted  to  it  should  be  carried 
out  in  a  tightly  closed  building  to  accommodate  not  more  than  fifty 
lambs  at  a  time.  Among  the  various  substances  which  have  been  used 
to  generate  the  fumes  are  tar,  creolin,  asafetida,  horns,-  hoofparings,  hair 
and  the  vapor  of  heated  oil  of  turpentine.  The  intensity  and  duration 
of  the  treatment  should  be  governed  by  the  size  and  vigor  of  the  animals 
and  according  as  they  become  accustomed  to  it.  At  first  it  should  not 
be  applied  for  more  than  a  few  minutes  each  day;  later  two  or  three 
treatments  of  ten  or  more  minutes  duration  each  may  be  given  daily. 
During  the  fumigation  the  animals  should  l)e  closol}'  watched  for  evi- 
dences of  asphyxiation. 

Of  agents  for  creating  the  fumes,  tar,  sulphur  and  turpentine  may  l^e 
mentioned  as  prol)ably  among  the  best.  These  may  be  placed  upon 
hot  coals  contained  in  a  pot  suspended  by  a  chain  from  the  ceiling  in 
such  manner  that  it  will  be  just  l)cyond  the  reach  of  the  animals'  heads. 
The  fumes  should  fill  the  entire  enclosure  and  can  be  maintained  by 
adding  more  of  the  ingredients  as  required. 

A  more  successful  method  of  treatment  is  by  tracheal  injections  of 
liquids  which  will  kill  the  worms  or  reduce  their  vitality  to  a  sufficient 
degree  that  they  may  be  easily  expelled.  This  procedure  is  espe- 
cially to  be  reconmiended  for  calves  and  is  equally  effectual  for  lambs, 
though  where  flocks  of  considerable  size  are  involved,  it  is  not  so 
practicable. 

The  measure  of  success  attauied  by  such  treatment  will  depend  largely 
upon  the  degree  to  which  the  worms  and  their  larvae  have  penetrated  to 
the  deeper  parts  of  the  respiratory  organs.  The  solutions  used  must 
reach  their  destination  l)y  gravity,  aided  somewhat  In-  the  currents  of 
inspired  air,  so  that  ultimately  they  will  probably  pass  no  further  than 


266  PARASITES  OF  THE  DOMESTIC  ANIMALS 

to  the  anterior  portions  of  the  lungs,  the  more  deeply  lodged  parasites 
remaining  unaffected.  Furthermore,  where  an  air  passage  is  occluded 
by  a  mucus  plug  and  mass  of  worms,  the  remedy  will  not  pass  beyond 
the  obstruction  and,  therefore,  cannot  reach  the  further  ramifications  of 
the  passage. 

Probably  aqueous  solutions  for  intratracheal  injection  have  an  ad- 
vantage in  more  readily  becoming  diffused.  Oily  preparations  do  not 
penetrate  so  deeply  nor  do  they  mix  with  the  mucus.  On  the  other  hand, 
it  is  to  be  said  in  their  favor  that  they  are  not  so  readily  absorbed  as 
aqueous  solutions  and  remain  in  the  air  passages  longer.  The  use  of 
both  aqueous  and  oily  mixtures  conjointly  might  well  be  recommended. 

Among  the  numerous  formulae  for  intratracheal  injection  the  following 
may  be  mentioned;  (1)  Iodine  two  parts,  iodide  of  potassium  ten  parts, 
distilled  water  one  hundred  parts.  Mix  and  inake  into  an  emulsion  with 
equal  parts  of  oil  of  turpentine  and  olive  oil.  Give  one  to  two  drams  to 
each  sheep;  calves  three  to  four  drams.  Two  injections  with  an  interval 
of  two  days  may  be  sufficient.  (2)  One  per  cent,  aqueous  solution  of 
carbolic  acid.  Sheep  one  to  one  and  a  half  drams,  calves  three  to  five 
drams.  Inject  once  daily  for  several  successive  daj^s.  (3)  Creolin  five 
parts,  oil  of  tupentine  and  olive  oil  of  each  fifty  parts.  Sheep  one  to 
one  and  a  half  drams,  calves  three  and  a  half  to  five  drams.  Inject  once 
daily  for  three  successive  da5'^s.  (4)  Creosote  twenty  parts,  oil  of  amyg- 
dala one  hundred  parts.  Calves  one  to  one  and  a  half  drams.  Inject 
once  daily  for  four  days. 

The  intratracheal  injections  should  be  made  slowly  with  a  curved 
needle  of  large  caliber  or  with  a  curved  trochar.  Previous  to  the  opera- 
tion the  wool  should  be  shaved  or  closely  clipped  from  the  region.  The 
needle  should  enter  between  the  tracheal  rings,  preferably  after  a  small 
incision  has  been  made  in  the  skin. 

Based  on  experiments  which  they  carried  on  for  over  one  year  (1914), 
involving  about  two  hundred  and  fifty  animals,  Herms  and  Freeborn 
concluded  that  chloroform  administered  nasally  is,  under  proper  condi- 
tions, a  valuable  method  of  treatment.  The  chloroform  is  introduced 
first  into  one  nostril,  then  into  the  other,  with  an  all  glass  syringe  or 
medicine  dropper  in  doses  sufficient  to  nearly  anaesthetize  the  animal,  or, 
in  other  words,  until  it  becomes  "groggy."  The  dosage  required  for 
this  will  depend  upon  the  animal's  susceptibihty,  and  therefore  cannot 
be  exactly  given.  It  is  stated  as  varying  from  twenty-three  to  forty-six 
drops  for  angora  goats,  and  from  sixty  to  one  hundred  and  sixty-five 
drops  for  calves,  one-half  the  quantity  in  each  nostril.  The  treatment  is 
to  be  repeated  at  five  or  six  day  intervals  until  recovery,  which,  under 
good  conditions  of  food  and  shelter,  should  not  require  more  than  three 
injections.  Experiments  by  the  investigators  mentioned  have  shown 
that,  while  the  worms  were  not  killed  immediately,  death  and  disin- 


METASTRONGYLIN^  267 

tegration  of  most  of  them  occurs  a  few  hours  after  the  administration  of 
the  chloroform  when  large  numbers  are  expelled  in  coughing. 

Whatever  procedure  maj^  be  adopted  in  the  treatment  of  bronchial 
and  pulmonary  strongylosis,  or  if  treatment  is  not  attempted,  it  is  highly 
important  that  the  animals  receive  plenty  of  nourishing  food  and  that 
they  be  well  sheltered  against  cold  and  wet  weather. 


CHAPTER  XXII 
NEMATODA.  SUBFAMILY  II.  TRICHOSTRONGYLINiE 

WOEMS    OF   THE    StOMACH   AND    INTESTINE 

Strongylidse  (p.  255). — These  strongyles  are  parasitic  only  in  the 
ahmentary  canal.  The  mouth  is  simple  and  without  a  buccal  capsule 
(Fig.  135).  The  body  is  generally  straight  or  it  may  be  somewhat 
curved.  The  eggs  are  generally  segmented  at  the  time  they  are  de- 
posited. Development  is  direct,  and  infection,  so  far  as  known,  is  only 
b}^  ingestion. 

Gastro-Intestinal  Strongylosis  of  the  Sheep  and  Goat 

1.  Haemonchus  contortus  (Strongylus  contortus).  Fig.  134. 
Trichostrongylinse  (p.  268). — The  body  is  filiform,  attenuated  at  the 
extremities,  and  red  or  white  in  color.  The  integument  is  striated 
transversely.  Near  the  anterior  extremity  there  are  two  lateral  tooth- 
like papillae  directed  backward.  The  bursa  of  the  male  has  two  long 
lobes  and  a  small  lobe  accessory  to  the  right  (Fig.  136);  there  are  two 
spicules.  The  tail  of  the  female  is  acutely  pointed;  anterior  extremity 
more  gradually  attenuated ;  vulva  toward  posterior  fifth  of  the  bod^'. 

Length  of  female,  18-30  mm.  (11/16-1  3/16  inches) ;  male,  10-20  mm. 
(3/8-3/4  of  an  inch). 

The  eggs  are  elongated  oval  and  measure  70-95  microns  long  by 
43-54  microns  wide.  According  to  Railliet  they  contain  developed 
embryos  at  the  time  of  deposition.  Hatching  probably  takes  place  in 
water,  the  embryo  at  the  time  of  its  release  measuring  300-400  microns 
in  length  by  17-21  microns  in  breadth.  Infection  is  probably  b}'  drinking 
water  and  contaminated  pasturage  bearing  the  larvae. 

The  worm  is  parasitic  in  the  abomasum  and  duodenum  of  sheep, 
goats,  and  cattle. 

2.  Cooperia  curticei  (Strongylus  ventricosus;  St.  curticei).  Fig. 
137.  Trichostrongylinse  (p.  268).— The  anterior  end  of  the  body  is 
usually  coiled  spirally.  The  cuticle  at  the  region  of  the  head  is  striated 
transversely;  cuticle  of  remainder  of  the  body  exhibits  fourteen  to  six- 
teen longitudinal  lines.  The  mouth  is  small  and  not  well  defined.  The 
bursa  of  the  male  has  two  lateral  lobes  and  a  small  median  lobe.  The 
spicules  are  short.  The  vulva  of  the  female  is  close  to  the  posterior  end 
of  the  body.    Tail  slender  and  acutely  pointed.     « 


TRICHOSTRONGYLIN.E 


269 


nv.l. 

Fig.  136. — Hsemonchus  contortus, — enlarged, 
Posterior  extremity  of  male,  dorsal  Aaew;  d. 
dorsal  ray  supporting  the  asymmetrically 
situated  dorsal  lobe  of  bursa;  e.  d.,  externo- 
dorsal  ray;  e.  1.,  externo-lateral  ray;  gub., 
gubernaculum;  1.  v.,  latero-ventral  ray;  m.  1., 
medio-lateral  ray;  p.  1.,  postero-lateral  ray; 
sp.,  spicule;  v.  v.,  ventro-vcntral  ray  (after 
Ransom,  Bull.  No.  127,  Bureau  An.  Ind.,  U.  S. 
Fig.      134.—  l:S::^^}^m,  Dept.  Agr.). 

Hsemonchus   con-  i        c  c  i         i  /     / 

tortus,      female.     Fig.  i35.-Ha5mon-      Length  oi  tcniale,  about  6  mm.  (1/4 
*Vuiva.  x5.   (Af-  chus   contortus,  an-  of  an  inch);  male  about  5  mm.  (3/16 

ter  Ransom,  Bull,  terior       portion       of 


No.  127,  Bu 
An.  Ind.,  U.  S 
Dept.  Agr.). 


body, — enlarged:  c. 
p.,  cervical  papilla; 
es.,  esophagus;  int., 
intestine;  n.  r.,  nerve 
ring  (after  Ransom, 
Bull.  No.  127,  Bu. 
An.  Ind.,  U.  S.  Dept. 
Agr.). 


of  an  inch). 

The  eggs  are  oval,  63-70  microns  in 
length  by  30-32  microns  in  width,  seg- 
mented at  time  of  deposition. 

The  worm  is  parasitic  in  the  small 
intestine,  more  rarely  the  abomasum, 
of  the  sheep  and  goat. 
3.  Ostertagia  marshalli.  Fig.  139.  Trichostrongylinae  (p.  268). — 
The  mouth  is  small  and  surrounded  b\'  six  indistinct  papillae.  The 
cuticle  has  twenty-five  to  thirty-five  longitudinal  ridges  appearing  as 
lines.  Cervical  papillae  340-415  microns  from  anterior  end  of  the  body. 
The  bursa  of  the  male  is  bilobate;  spicules  short  and  similar,  yellowish 
brown  in  color.  The  tail  of  the  female  is  slender,  gradually  tapering, 
and  rounded  at  the  tip.  The  \ailva  is  a  transverse  slit  located  near  the 
tail  extremitv. 


270 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Fig.  137. — Cooperia  curticei;  male  at 
right,  female  at  left.  *Vulva.  xl5. 
(After  Ransom,  Bull.  No.  127,  Bureau 
An.  Ind.,  U.  S.  Dept.  Agr.). 


Fig.  139. — Ostertagia  marshalli;  male  at  right,  female  at 
left,  enlarged  (after  Ransom,  Bull.  No.  127,  Bureau  An.  Ind., 
U.  S.  Dept.  Agr.). 


m 


Fig.  138.— Co- 
operia curticei, 
anterior  portion 
of  body,  lateral 
view.  x300.  (Af- 
ter Ransom,  BuU. 
No.  127,  Bureau 
An.  Ind.,  U.  S. 
Dept.  Agr.). 


TRICHOSTRONGYLIN.E 


271 


Length  of  female,  12-20  mm.  (1/2-3/4  of  an  inch);  male,  10-13  mm. 
(3/8-1/2  an  inch). 

The  eggs  are  oval,  160-200  microns  in  length  by  75-100  microns  in 
breadth. 

The  worm  is  parasitic  in  the  abomasum,  rareh^  the  small  intestine, 
of  the  sheep.  It  was  first  collected  by  Dr.  H.  T.  Marshall  and  Prof. 
V.  K.  Chestnut  in  Montana. 

4.  Trichostrongylus  instabilis  (Strongylus  colubrif ormis ;  St.  in- 
stabilis).  Fig.  140.  Trichostrongylina?  (p.  2r)S).^The  body  is  small, 
slender,  gradually  attenuated  forward  from 
posterior  fifth;  color  reddish.  Cuticle  trans- 
versely striated ;  longitudinal  lines  and  cer- 
vical papilla3  absent.  The  bursa  of  the 
male  is  large  and  laterally  lobed;  spicules 
short,  spatulate,  and  appearing  as  though 
twisted.  The  body  of  the  female  is  but 
slightly  thinner  toward  the  anus;  behind 
the  anus  it  suddenly  narrows  to  form  a 
sharp  tail;  vulva  near  middle  of  posterior 
half  of  the  body. 

Length  of  female,  5-6  mm.  (1/4  of  an 
inch) ;  male,  4-5  mm.  (3/16  of  an  inch). 

The  eggs  are   oval,   73-76  microns 
length  by  40-43  microns  in  breadth. 

The  worm  is  parasitic  in  the  duodenum 
of  sheep  and  goats  of  North  Africa,  Europe, 
Japan,  and  United  States.  In  Egypt  it 
has  been  observed  in  man. 

Other  species  which  may  be  found  in 
sheep  and  goats  are  Nematodirus  filicollis 
and  Cooperia  oncophora  which  are  referred 

to  under  gastro-intestinal  strongylosis  of  som,  Bull.  No.  127,  Bureau  An. 
cattle.  Ind..U.S.Dept.Agr.). 

Occurrence. — Gastro-intestinal  strongylosis  of  sheep  and  goats  is 
generally  caused  by  the  presence  of  Hccmonchiis  contortiis  which  may 
be  in  association  with  one  or  more  other  species.  This  stomach  worm 
is  recognized  as  one  of  the  most  serious  of  the  numerous  pests  with 
which  the  sheep  raiser  has  to  contend.  Animals  of  all  ages  become 
infected,  but  the  most  serious  effects  are  observed  in  lambs  and  kids. 
Occurring  mostly  in  wet  marsh}'  districts  and  in  seasons  of  frequent  rain 
— conditions  favorable  to  the  propagation  of  the  lung  as  well  as  the 
gastric  worms — the  affection  is  frequently  associated  with  the  respiratory 
form  of  strongylosis. 

In  the  United  States  the  stomach  worm  of  sheep,  goats,  and  cattle 


Fig.  140. — Trichostrongylus  in- 
stabilis; male  at  right,  female  at 
left.—*  Vulva.    xl5.    (After   Ran- 


272  PARASITES  OF  THE  DOMESTIC  ANIMALS 

is  especially  prevalent  in  the  Mississippi  Valley,  in  the  region  of  rivers 
tributar}^  to  the  Mississippi,  and  in  the  Gulf  States.  In  parts  of  the 
Middle  AVest  and  South  the  parasite  has  been  such  a  source  of  discour- 
agement as  to  cause  the  sheep  industry  to  be  almost  completely  aban- 
doned. 

Pathogenesis. — Taken  up  as  larvte  with  ingested  plants  or  drinking 
water,  the  worms  attack  the  mucosa  of  the  fourth  stomach  and  feed 
upon  the  blood  of  their  host.  The  degree  of  disturbance  which  they 
cause  will  be  proportionate  to  their  number.  Heavy  infestations  are 
accompanied  by  disorders  of  digestion  and  lead  through  loss  of  blood 
to  anemia,  dropsy,  and  emaciation,  the  general  morbid  effect  being 
contributed  to  b}^  the  toxins  elaborated  by  the  parasites. 

Symptoms. — The  symptoms  are  those  of  a  pernicious  anaemia.  The 
infected  animal  becomes  dull  and  spiritless  and  there  is  arrested  develop- 
ment. The  appetite  is  diminished  and  depraved,  and  the  animal  fre- 
quently seeks  water  to  quench  an  intense  thirst.  The  anaemia  is  revealed 
in  the  paleness  of  the  skin  and  visible  mucous  membranes  and  in  the 
edematous  swellings  in  dependent  parts  of  the  body,  often  under  the 
lower  jaw.  Later  in  the  course  of  the  disease  a  diarrhea  appears  with 
Avatery  dark  discharge  of  putrid  odor.  In  some  cases  the  toxic  disturb- 
ances may  be  manifested  by  convulsions  or  paralysis.  Finally,  after  a 
course  of  several  months,  the  animal  dies  in  a  state  of  extreme  emacia- 
tion and  weakness. 

The  cause  of  these  symptoms  of  a  progressive  anaemia  can  often  be 
no  more  than  suspected,  and,  where  the  condition  prevails  in  flocks,  a 
more  certain  diagnosis  may  be  made  by  killing  an  affected  animal  and 
examining  the  fourth  stomach. 

For  Post-mortem  Appearance,  Development,  Control,  and  Treat- 
ment, refer  to  pp.  275-279. 

Gastro-Intestinal  Strongylosis  of  Cattle 

Several  species  of  strongyles  may  occur  in  the  abomasum  of  cattle- 
Of  these  the  most  important  are  Hcemonchus  contortus,  described  under 
gastro-intestinal  strongylosis  of  sheep,  and  the  encj^sted  stomach  worm, 
Ostertagia  ostertagi. 

1.  Ostertagia  ostertagi  (Strongylus  ostertagi).  Fig.  141.  Tricho- 
strongylinae  (p.  268). — The  body  is  filiform  with  attenuated  extremities. 
The  mouth  is  small  and  surrounded  by  six  indistinct  papillae;  cervical 
papillae  present.  The  cuticle  has  25  to  35  longitudinal  lines  or  ridges. 
The  bursa  of  the  male  is  comparatively  small  and  has  two  lateral  lobes 
united  bj'  a  small  median  lobe  (Fig.  142).  The  spicules  are  short,  each 
having  two  slender  barbed  processes  coming  off  from  the  inner  side  in 
the  posterior  half.    The  vulva  of  the  female  is  a  transverse  slit  covered 


TRICHOSTROXGYLIX.E 


273 


\n^ i-s/x 


.p.bp. 


Fig.  142. — Ostertagia  ostertagi. 
Posterior  extremity  of  male  with 
bursa  spread  out:  d,  dorsal  ray;  e.  d., 
externo-dorsal  ray;  p.  1.,  postero- 
lateral ray;  m.  1.,  medio-lateral  ray; 
e.  1.,  externo-lateral  ray;  1.  v.,  latero- 
ventral  raj-;  v.  v.,  vontro-ventral  ray; 
p.  b.  p.,  pre-bursal  papilla;  sp.,  spi- 
cules. xloO.  (After  Ransom,  from 
Railliet,  Bull.  No.  127,  Bureau  An. 
Ind.,  U.  S.  Dept.  Agr.). 

b}'  a  prominent  cuticiilar  flap;  it  is  located 
close  to  the  caudal  extremity  of  the  body. 
The  tail  tapers  gradually  and  ends  in  a  slen- 
der tip. 

Length  of  female,,  8-10  mm.  (5/16-3/8  of 
an  inch) ;  male,  7-8  mm.  (1/4-5/16  of  an  inch.) 

The  eggs  are  oval,  65-80  microns  in  length 
by  30-40  microns  in  breadth. 

The  worm  is  parasitic  in  the  wall  and  cavity  of  the  abomasum  of 
cattle. 

2.  Nematodirus  filicoUis  (Strongylus  filicoUis).  Fig.  143.  Tricho- 
strongylinae  (p.  268). — This  is  a  white  hair-like  worm,  very  thin  in  front, 
thicker  behind.  The  cuticle  has  eighteen  longitudinal  ridges.  The 
bursa  of  the  male  is  bilobate;  there  are  two  very  long  and  slender  spicules 
united  by  a  membrane  posteriorly  which  forms  a  spatulate  enlargement 
at  the  tip.  The  \iilva  of  the  female  is  a  transverse  slit  located  about 
one-third  of  the  length  of  the  body  from  the  caudal  e.xtremity.  At  this 
location  the  bodv  has  its  maximum  thickness  which  is  suddenly  reduced 


Fig.    141. — Ostertagia    oster- 
tagi;  male  at  right,  female   at 


left, 
som, 
Ind. 


*  Vulva.  xl5.  (After  Ran- 
BuU.  No.  127,  Bureau  An. 
U.  S.  Dept.  Agr.). 


Fig.  143. — Nematodirus  filicollis;  male  in  center,  female  at  left.  *  Vulva.  xl5.  At 
right,  enlarged  anterior  portion  of  body.  (After  Ransom,  Bull.  No.  127,  Bureau  An.  Ind., 
U.  S.  Dept.  Agr.). 


Fig.  144. — Cooperia  oncophora;  male  at  right,  female 
at  left.  *  Vulva.  xl5.  (After  Ransom,  Bull.  No.  127, 
Bureau  An.  Ind.,  U.  S.  Dept.  Agr.). 


TRICHOSTRONGYLIX.E  275 

just  behind  the  vulva.  The  tip  of  the  tail  is  truncate  and  bears  a  short 
bristle-like  process. 

Length  of  female,  10-24  mm.  (3/8-15/16  of  an  inch);  male,  8-13  nmi. 
(5/16-1/2  of  an  inch). 

The  eggs  are  elongated  oval,  110-113  microns  in  length  b}'  64-70 
microns  in  breadth;  segmented  at  time  of  deposition.  The  further 
development  is  not  known. 

The  worm  is  parasitic  in  the  small  intestine  of  cattle,  sheep,  and  goats. 

3.  Cooperia  oncophora  (Strongylus  oncophora).  Fig.  144.  Tricho- 
strongylina'  (p.  268). — The  head  is  rounded,  without  well-marked  papil- 
lae; mouth  cavity  small  and  not  well  defined.  The  cuticle  in  the  region  of 
the  head  is  transversel.y  striated;  cuticle  of  remainder  of  body  with  14- 
16  longitudinal  lines  or  ridges;  cervical  papillae  absent.  The  bursa  of 
the  male,  when  spread,  is  large  and  has  two  lateral  lobes  and  a  small 
median  lobe;  border  of  median  lobe  incised.  The  spicules  are  short 
and  of  comparatively  simple  structure.  The  vulva  of  the  female  is  in 
the  posterior  fourth  of  the  body.  At  the  region  of  the  vulva  the  body  is 
much  enlarged.  The  tail  is  slender  with  rounded  tip;  terminal  portion 
of  tail  marked  with  annular  striations. 

Length  of  female,  6-8  mm.  (5/16  of  an  inch) ;  male  about  the  same. 

The  eggs  are  oval,  60-80  microns  in  length  by  30  microns  in  width. 

Inhabits  the  small  intestine  of  cattle  and  sheep. 

Occurrence  and  Symptoms. — Haemonchus  contortus  is  frequently 
found  in  the  al)omasum  of  cattle.  When  the  infestation  is  heav}',  which 
usually  occiu's  in  young  pastured  animals,  they  bi'ing  about  the  sjniip- 
toms  of  a  pernicious  anaemia  as  descriljed  in  the  infestation  of  sheep. 
The  cattle  become  infected  ])y  grazing  upon  pastures  which  are  contam- 
inated by  the  di'oppings  of  infected  sheep,  goats,  or  other  infested  cattle. 

The  s\Tuptoms  caused  by  the  presence  of  Ostertagia  ostertagi,  or  the 
cncj^sted  stomach  worm,  are  similar  to  those  produced  Ijj"  Hcemonchus 
contortus.  It  lives  in  small  cysts  in  the  mucosa  of  the  abomasum  and 
is  also  found  free  in  the  contents  of  this  organ.  When  numerous,  they 
cause  a  catarrhal  condition  and  disturbances  of  digest-ion. 

For  Post-mortem  Appearance,  Development,  Etiology,  Control,  and 
Treatment  refer  to  pp.  275-279. 

Gastro-Intestixal  Strongylosis.    Post-AIortem  Appearance 

Examination  of  the  contents  of  the  abomasum  and  duodenum  from 
an  animal  which  has  been  heavily  infested  with  stomach  strongyles 
will  reveal  undulating  movements  of  the  fluitl  produced  by  the  active 
wriggling  a})Out  of  the  worms.  Large  num])ers  will  also  be  found  deeply 
adhering  to  the  mucosa  which  will  show  the  lesions  of  a  subacute  or 
chronic  catarih.    Further  than  this,  the  pernicious  anaemia  is  evidenced 


276  PARASITES  OF  THE  DOMESTIC  ANIMALS 

in  the  paleness  of  the  body  tissues,  edematous  swelHngs,  exudate  into 
the  serous  cavities,  and  cachexia. 

Where  Ostertagia  ostertacji  are  present  in  the  abomasum  of  cattle  they 
will  be  found  both  free  in  the  stomach  contents  and  embedded  in  the 
subepithelial  tissue  of  the  mucosa  in  small  round  cysts  about  the  size 
of  a  pin-head  or  slightly  larger.  When  numerous,  the  same  lessions  are 
shown  as  in  the  attack  upon  the  mucosa  of  a  heaw  invasion  with  Hcemon- 
chiis  contortus. 

Gastro-Intestinal  Strongylosis.    Development  and  Etiology 

The  eggs  of  Hoemonchus  contortus  passed  in  the  feces  of  the  host  will 
hatch  in  a  variable  time  according  to  the  conditions  of  temperature  and 
moisture.  When  these  are  favorable  it  may  occur  in  a  few  hours,  while, 
under  more  adverse  conditions,  it  may  take  several  days  or  weeks. 
Drj^ness  or  a  freezing  temperature  kills  the  embryos  and  newly  hatched 
larvae  in  a  short  time.  Upon  hatching  the  larva  feeds  upon  the  fecal 
matter  with  which  it  is  surrounded.  Later  it  becomes  enveloped  by  a 
chitinous  sheath,  in  this  condition  probably  receiving  nourishment 
from  food  material  stored  within  its  body.  At  this  stage  the  larva  can 
survive  freezing  and  drying  for  long  periods  and  is  motile  at  temperatures 
above  40°  F.,  becoming  more  active  with  increase  in  temperature.  Where 
there  is  sufficient  moisture,  as  from  dew  or  rain,  it  crawls  upon  a  blade 
of  grass  or  other  vegetation  and  gradually  makes  its  way  to  a  position 
well  removed  from  the  ground.  In  this  position  it  is  taken  up  by  the 
grazing  ruminant  host  and,  reaching  the  abomasum,  becomes  mature  in 
two  to  four  weeks.  If  the  eggs  or  newly  hatched  larvce  are  ingested 
they  apparently  do  not  undergo  further  development.  It  seems,  there- 
fore, that  only  the  ensheathed  larvae  are  infective. 

Control. — As  stated  in  the  foregoing,  moisture  favors  the  develop- 
ment of  the  embryos,  while  dryness  kills  them  at  their  early  stages. 
High  pasture  ground,  therefore,  with  good  natural  drainage  greatly 
reduces  the  chances  of  the  larvae  reaching  the  infective  stage.  Further- 
more, larvae  which  have  become  infective  are  more  motile  in  the  presence 
of  moisture  such  as  is  supplied  by  the  heavy  dews  and  fogs  occurring 
over  low  land;  crawling,  then,  out  upon  the  wet  blades  of  grass,  the 
worms  are  more  likely  to  be  taken  up  by  the  grazing  animals. 

If  the  temperature  remains  constantly  at  about  95°  F.  the  infective 
larval  stage  is  reached  in  three  to  four  days  after  the  eggs  have  passed 
from  the  body  of  the  host.  At  70°  F.  one  to  two  weeks  are  required, 
while  three  to  four  weeks  are  necessary  at  about  50°  F.  At  temperatures 
below  40°  F.  the  eggs  are  dormant  and  the  larvae  remain  inactive.  Under 
the  usual  climatic  conditions  of  the  northern  part  of  the  United  States, 
therefore,  there  is  little  possibility  of  new  infection  from  placing  in- 


TRICHOSTRONGYLIN^  277 

fectecl  and  noninfected  animals  together  in  clean  fields  from  the  first 
of  November  until  March. 

During  the  warmer  months  the  best  means  of  controlling  the  parasite 
seems  to  be  by  the  rotation  of  pastures,  keeping  each  pasture  free  from 
sheep  and  cattle  for  at  least  a  3'ear,  by  which  tmie  the  larvffi  will  be  dead. 
As  to  this  method  Ransom  (U.  S.  B.  A.  I.,  Cir.  No.  102)  suggests  the 
following:  "Infested  and  nonmfested  sheep  which  have  been  kept  to- 
gether in  clean  fields  from  November  to  March  or  later,  according  to 
weather,  if  moved  then  to  another  clean  field  may  remain  there  nearly 
the  entire  month  of  April  before  there  is  danger  of  infection.  From  the 
first  of  Ma}'  on  through  the  summer  the  pastures  become  infectious  much 
more  quickly  after  infested  sheep  are  placed  upon  them,  and  during 
May  it  would  be  necessary  to  move  the  sheep  at  the  end  of  every  two 
weeks,  in  June  at  the  end  of  everj^  ten  days,  and  in  July  and  August  at 
the  end  of  each  week,  in  order  to  prevent  the  noninfected  sheep  from 
becoming  infected  from  the  worms  present  in  the  rest  of  the  flock. 
After  the  first  of  September  the  period  maj^  again  be  lengthened." 

The  difficulties  and  inconveniences  of  this  method  consist  in  the  num- 
ber of  small  pastures  and  subdivisions  of  pastures  which  it  requires; 
furthermore,  it  imposes  limitations  upon  the  size  of  the  flock.  It  is, 
however,  probably  the  most  effective  system  thus  far  devised  for  the 
eradication  of  this  parasite. 

Where  it  can  be  convenientl.y  practiced,  it  is  a  good  precautionarj^ 
measure  to  burn  over  the  pastures  in  the  early  spring  or  fall.  This  will 
destroy  most  of  the  eggs  and  larvae  which  are  lodged  upon  the  grass  or 
upon  the  ground. 

Treatment. — Experiences  recorded  with  the  use  of  drugs  for  the 
expulsion  of  stomach  worms  are  somewhat  varied.  The  success  attained 
by  such  treatment  has  not  equaled  expectations  based  upon  experiments 
made  with  the  agents  upon  worms  outside  of  the  bod}'-  of  a  host.  It  is 
probable  that  this  is  mainly  due  to  the  fact  that  drugs  administered  to 
ruminants  by  the  mouth  do  not  pass  directly  to  the  abomasum,  but  must 
first  mix  with  the  ingesta  of  the  rumen  and  reticulum,  passing  from  the 
latter  by  way  of  the  omasum  to  the  abomasum  and  intestine.  Hence, 
before  reaching  the  worms  the  drug  become  sufficiently  diluted  or  mixed 
with  the  bulky  ingesta  to  greatly  reduce  its  effectiveness.  Treatment 
for  the  expulsion  of  Hcemonchus  contortus  gives  better  promise  for  success 
than  that  for  the  smaller  stomach  strongjdes,  as  Ostertagia  ostertagi, 
owing  to  the  protected  position  of  the  latter  within  the  nmcosa. 

Animals  which  are  to  be  treated  should  be  taken  up  in  the  afternoon 
of  the  day  previous  to  treatment  and  all  food  withheld  from  them  for 
eighteen  to  twenty-two  hours.  The  remedy  should  be  given  the  following 
morning  either  with  a  long-necked  bottle  or,  better,,  with  a  drenching 
tube  consisting  of  about  three  feet  of  one-half  inch  rubber  tubing  with 


278  PARASITES  OF  THE  DOMESTIC  ANIMALS 

a  funnel  inserted  at  one  end  and  a  four  to  six  inch  piece  of  metal  tubing 
inserted  in  the  other  end,  the  metal  tube  to  be  placed  in  the  animal's 
mouth  between  the  molar  teeth.  The  funnel  may  be  held  by  an  assistant 
or  fastened  to  a  post  while  receiving  the  liquid,  the  flow  of  which  may  be 
controlled  by  pinching  the  rubber  tube  near  the  insertion  of  the  metal 
piece.  The  dosage  for  each  sheep  should  be  carefully  measured  accord- 
ing to  age,  and  care  taken  to  lower  the  head  at  once  upon  entrance  of 
the  liquid  into  the  larynx,  this  often  a  result  of  holding  the  head  too  high 
and  indicated  by  coughing. 

Among  the  remedies  used  for  the  expulsion  of  stomach  worms  may 
be  mentioned  (1)  copper  sulfate,  (2)  gasoline,  and  (3)  coal-far  creosote. 
An  objection  to  the  last  named  is  its  variable  composition,  the  substance 
not  infrequently  sold  under  the  name  of  coal-tar  creosote  being  quite 
unreliable  for  the  purpose  here  considered.  Copper  sulfate  has  received 
high  recommendation  and  is  extensively  used  in  the  sheep  flocks  of 
South  Africa.    It  ma}^  be  prepared  and  given  as  follows: 

Dissolve  1/4  of  a  pound  (avoirdupois)  of  clear  blue  crystals  of  copper 
sulfate  in  one  pint  of  boiling  water,  having  first  crushed  the  crystals  in 
a  mortar  to  a  fine  powder.  In  making  the  solution  use  a  porcelain  or 
enamel-ware  vessel  as  the  bluestone  will  corrode  most  metals.  Add  to 
this  solution  enough  cold  water  to  make  it  up  to  three  gallons,  using 
non-metallic  receptacles.  This  will  make  an  approximate  one  per  cent, 
solution,  and,  allowing  for  waste,  will  be  enough  for  the  treatment  of 
about  one  hundred  adult  sheep. 

The  dosage  is  to  be  graded  according  to  age  as  follows : 

Lambs  3  months  to  1  year  old 5  drams  to  11/2  oz.  (20-50  cc). 

Sheep  over  1  year  old 2  to  3  oz.  (64  to  96  cc). 

Calves 3  to  4  oz.  (96  to  128  cc). 

Yearling  cattle 6  oz.  (192  cc). 

The  annuals  should  receive  no  water  at  any  time  during  the  day  the^' 
are  dosed. 

"NMiere  the  stomach  worm  exists  in  a  fiock,  it  has  been  suggested  as  a 
control  measure  to  give  50  cc  of  a  one  per  cent,  solution  of  copper 
sulfate  every  month  or  so  except  during  the  winter  in  climates  where 
the  winter  is  freezing. 

Gasohne  has  afforded  a  convenient  remedy,  but,  for  reasons  which 
need  not  be  gone  into  here,  the  commercial  gasoline  of  the  present  time 
is  unsuitable  for  this  purpose.  Under  such  conditions  onty  the  official 
purified  gasoline  (benzinum  purificatum,  U.  S.  P.)  should  be  used.  At 
best,  however,  gasolme  is  probably  less  satisfactory  for  the  purpose 
than  copper  sulfate;  furthermore,  to  be  effectual,  the  gasoline  treatment 
must  be  repeated  upon  three  consecutive  days. 

In  the  preparation  for  the  administration  of  gasoline  withhold  water 


TRICHOSTRONGYLIN.E  279 

as  well  as  feed.  The  following  morning  give  the  gasoline  in  milk,  linseed 
oil,  or  flaxseed  tea,  mixing  the  dose  for  each  animal  according  to  age  as 
follows : 

Lambs 2  drams  (8  cc). 

Sheep 4  drams  (16  cc). 

Calves 4  drams  (16  cc). 

Yearling  cattle 1  oz.  (32  cc). 

Three  hours  later  allow  feed  and  water.  At  night  again  confine  the 
animals  without  feed  and  water.  The  next  morning  give  the  second 
dose,  the  third  morning  the  third  dose,  the  treatment  before  and  after 
dosing  being  the  same  in  each  case.  Gasoline  should  not  be  given  in 
water,  nor  should  it  be  given  soon  after  the  animals  have  taken  water. 

Coal-tar  creosote  may  be  given  in  solution  of  one  per  cent,  strength. 
The  solution  is  made  by  shaking  together  one  ounce  of  coal-tar  creosote 
and  ninety-nine  ounces  (6  pints  and  3  ounces)  of  water.  The  doses  of 
this  as  recommended  by  Stiles  are  as  follows: 

Lambs  4  to  12  months  old 2  to  4  ounces 

Yearling  sheep  and  above 3  to  5  ounces 

Calves  3  to  8  months  old 5  to  10  ounces 

Yearling  steers 1  pint 

Two-3' ear-olds  and  above "...  1  quart 

If  a  good  qualitA'  of  coal-tar  creosote  is  used,  good  results  may  l)e 
obtained  from  a  single  dose  of  this  one  per  cent,  solution. 

Other  remedies,  such  as  lysol  and  arsenic,  have  been  recommended 
by  various  authors,  but  probably  the  most  effectual  will  come  within 
those  which  have  been  particularly  mentioned. 

The  treatment  should  be  administered  to  the  entire  herd,  since  an- 
imals which  may  be  but  lightly  infested  will  remain  a  source  of  reinfec- 
tion to  others. 

The  general  condition  of  the  animals  should  be  built  up  and  main- 
tained by  a  generous  supply  of  nourishing  food  and  thoy  should  receive 
a  plentiful  supply  of  salt. 


CHAPTER  XXIII 
NEMATODA.  SUBFAMILY  III.  STRONGYLIN^ 

Worms  of  the  Large  and  Small  Intestines;  Other  Strongyles 

These  worms  are  parasitic  in  the  digestive  tract,  rarely  in  the  respi- 
ratory organs.  The  buccal  capsule  is  present.  The  bursa  of  the  male 
is  well  developed  and  has  one  or  two  dorsal  rays  and  two  lateral  ray 
systems  of  six  rays  each.  There  are  two  spicules.  The  vulva  of  the 
female  is  usually  posterior  to  the  middle  of  the  body,  but  may  be  anterior 
to  the  middle.    There  are  two  ovaries. 

The  eggs  are  segmented  at  the  time  they  are  deposited.  The  embryos 
are  rhabditiform.  The  development,  so  far  as  known,  is  direct.  In 
some  forms  the  development  is  complex,  involving  a  nodular  phase  or 
larval  migration. 

Based  mainly  upon  the  formation  of  the  bursal  rays  and  the  location 
of  the  vulva,  the  Strongylinse  have  been  grouped  by  Railliet  and  Henry 
into  five  tribes,  as  follows : 

Tribe     I.  OEsophagostomese 

Tribe   II.  Strongyleae  (Ankylostomese) 

Tribe  III.  Bunostomese 

Tribe  IV.  Cylicostomese 

Tribe     V.  Syngameae 

I.  (Esophagostomeae.  Strongyhnae  (p.  280). — The  bursa  of  the  male 
has  two  lateral  lobes  united  by  a  smaller  median  lobe.  In  each  lateral 
lobe  there  are  six  rays.  The  ray  of  the  median  lobe  divides  into  two 
main  branches,  each  of  which  again  divides  into  two.  The  vulva  of 
the  female  is  situated  a  short  distance  in  front  of  the  anus;  uteri  diver- 
gent.   The  tribe  includes  three  genera,  as  follows : 

Genus      I.  (Esophagostomum 
Genus    II.  Chabertia  (Sclerostomum) 
Genus  III.  Agriostomum 

II.  StrongyleaB.  Strongylinse  (p.  280). — The  ventral  and  latero- 
ventral  rays  of  the  lateral  bursal  lobes  are  close  together  and  parallel. 
The  medio-lateral  and  postero-lateral  rays  are  not  close  together  and 
parallel.  The  dorsal  raj^  ends  in  tridigitate  terminations.  The  vulva 
of  the  female  is  situated  in  the  posterior  third  of  the  body;  uteri  diver- 
gent.   The  tribe  includes  four  genera,  as  follows: 

Genus      I.  Strongylus 

Genus    II.  Ankylostoma 

Genus  III.  Uncinaria 

Genus  IV.  Characostomum 


STROXGYLIX.E]  281 

III.  Bunostomeae.  Strongylinae  (p.  280).— The  ventral  and  latero- 
ventral  rays  of  the  bursal  lobes  are  close  together  and  parallel.  The 
medio-lateral  and  posterolateral  rays  are  not  close  together  and  are 
not  parallel.  The  dorsal  ray  ends  in  a  bifurcation.  The  vulva  of  the 
female  is  situated  in  the  middle  of  the  body  or  a  httle  anterior  to  the 
middle;  uteri  divergent.    The  tribe  includes  four  genera,  as  follows: 

Genus     I.  Bunostomum 
Genus    II,  Gaigeria 
Genus  III.  Bathmostonunn 
Genus  IX.  Grammocephalus 

IV.  Cylicostomeae.  Strongyhnae  (p.  280).— The  ventral  and  latero- 
ventral  raj's  of  the  bursal  lobes  are  close  together  and  parallel.  The 
medio-lateral  and  postero-lateral  raj's  are  not  close  together  and  parallel. 
The  dorsal  and  externo-dorsal  rays  originate  separately.  The  vulva 
of  the  female  is  situated  close  to  the  anus;  uteri  convergent.  The  tribe 
includes  four  genera,  as  follows: 

Genus     I.  Cylicostomum 

Genus    II.  Q^sophagodontus 

Genus  III.  Gyalocephalus 

Genus  IV.  Triodontophorus 

Y.  Syngameae.  Strongylinse  (p.  280). — The  bursa  is  obhquely  trun- 
cated. The  anterior  and  middle  rays  are  cleft,  the  posterior  tridigitate. 
The  vulva  of  the  female  is  situated  in  the  anterior  quarter  of  the  body; 
uteri  divergent.    The  tribe  includes  one  genus — Syngamus. 

XODULAR    StROXGYLOSIS    OF    THE    ShEEP    AND    GOAT.       CEsOPHAGOSTO- 

MIASIS 

1.  (Esophagostomum  columbianum.  Fig.  145.  Strongylinse  (p. 
280). — The  thickness  of  the  body  is  nearly  uniform  over  its  greater 
portion;  attenuated  toward  ends.  The  anterior  portion  is  usually 
curved  in  the  form  of  a  hook.  The  cuticle  surroimding  the  mouth  is 
inflated  to  form  a  collar  which  has  ahnost  the  shape  of  a  hemisphere. 
Six  circum-oral  papillse  penetrate  this  mouth  collar.  In  front  of  the 
middle  of  the  esophagus  there  is  a  transverse  groove  with  accompanying 
cuticular  fold  extending  around  the  body  to  the  lateral  lines.  There  are 
two  cervical  papillae  in  front  of  the  middle  of  the  esophagus.  Posterior 
to  the  cervical  groove  are  two  lateral  membranes  which  extend  well 
back  along  the  lateral  lines.  The  bursa  of  the  male  has  two  lateral  lobes 
united  by  a  small  median  lobe.  The  spicules  are  750-850  microns  in 
length,  slender  and  pointed.  The  ^^lva  of  the  female  is  naked,  trans- 
versely elongated,  and  situated  a  short  distance  in  front  of  the  anus. 

The  length  of  the  female  is  14-18  mm.  (9/16-11  16  of  an  inch);  male, 
12-15  mm.  (1  '2-19  '32  of  an  inch). 


28^2 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Fig.  145. — -ffisophagostomum  columbianum;  male 
at  left,  female  at  right.  *  Vulva.  x5.  (After  Ran- 
som, Bull.  No.  127,  Bureau  An.  Ind.,  U.  S.  Dept. 
Agr.). 


The  eggs  are  oval,  65-75   microns  in      Fig.  146. 
length    by    40-45    microns    in    breadth,  "'"'^i^^""^- 


ffisophagostomum  col- 
Anterior      extremity, 
ventral  view, — enlarged:  c.  g.,  cer- 

Segmentation  occurs  while  thej^  are  within  vical  groove;  c.  p.,  cervical  papilla; 

the  uterus.  ^^•'  esophagus;  int.,  intestine;  1.  m. , 

mi        i-         1           1  ^r>^         •     lateral  membrane;  1.  p.,  lateral  cir- 

The    freed    embiyos  measure    230    mi-  eumoral  papilla;  m.  c,  mouth  collar; 

crons  in  length.  n.  r.,  nerve  ring.     (After  Ransom, 

Parasitic  in  the  large  intestine  of  the  ?"ii-  i^o-  127,  Bureau  An.  Ind.. 

,  ,  ^  ^  U.  S.  Dept.  Agr.). 

sheep  and  goat. 

2.  CEsophagostomum  venulosum.    Fig.  148.     Strongylina?  (p.  280). 

kJ^        — The  thickness  of  the  body  is  nearly  uniform  over  its  greater  portion, 

'  \.--' attenuated  toward  ends.     The  anterior  end  is  usually  straight.     The 

^J^     height  of  the  cuticular  collar  about  the  mouth  is  about  one-third  of  its 

diameter.    The  cuticle  of  the  neck  is  inflated  between  the  mouth  collar 

and  the  cervical  groove.    The  lateral  membranes  extend  well  back  but 

.are  very  narrow.    The  bursa  of  the  male  has  two  lateral  lobes  united  by  a 

small  median  lobe.    The  spicules  are  1.1-1.5  mm.  long.    The  vulva  of 

the  female  is  naked  and  located  just  in  front  of  the  anus.    From  a  short 

distance  in  front  of  the  vulva  the  body  tapers,  terminating  in  a  sharply 

pointed  tip. 

The  female  is  18-24  mm.  (23/32-15/16  of  an  inch)  in  length;  male, 
12-16  mm.  (15/32-5/8  of  an  inch). 

The  eggs  are  oval,  90  microns  in  length  by  55  microns  in  breadth. 


STRONGYLIN^ 


283 


Fig.  147. — CEsophago.sto- 
mum  columbianum.  En- 
larged bursa  of  male  viewed 
from   right   side:    d,    dorsal 


e.  1.,  extenio-lateral 
1.  v.,  latero-ventral 
m.  1.,  medio-lateral 
p.  1.,  postero-lateral 
V.  v.,  ventro-ventral 
(After  Ran.som,  Bull. 

No.  127,  Bureau  An.  Ind., 

U.  S.  Dept.  Agr.). 


raj'; 
ray; 
ray; 
ray; 
ray; 
ray. 


Fig.  150. 


Fig.  148.— (Esopha- 
gostomum  venulosum ; 
male  at  right,  female 
at  left.  *  Vulva.  x5. 
(After  Ransom,  Bull. 
No.  127,  Bureau  An. 
Ind.,  U.  S.  Dept.  Agr.). 


Fig.  150.  —  GEsopha- 
gostomum  venulosum. 
Enlarged  bursa  of  male 
viewed  from  right  side: 
d.,  dorsal  ray;  e.  d.,  ex- 
tcrno-dorsal  ray;  e.  1., 
oxterno-lateral  ray;  m. 
1.,  medio-lateral  ray; 
p.  1.,  postero-lateral  ray; 
sp.,  spicules;  v.  v.,  ven- 
tro-ventral ray.  (After 
Ransom,  Bull.  No.  127. 
Bureau  An.  Ind.,  U.  S. 
Dept.  Agr.). 


Fig.  149. — CEsopha- 
gostomum  venulosum. 
Anterior  portion  of 
body — enlarged,  ventral 
view:  c.  g.,  cervical 
groove;  c.  i,  cervical  in- 
flation; c.  p.,  cervical 
papilla;  es.,  esophagus; 
int.,  intestine;  1.  m., 
lateral  membrane;  1.  p., 
lateral  circumoral  pa- 
pilla; m.  c,  mouth  col- 
lar; n.  r.,  ners'e  ring. 
(After  Ransom,  Bull. 
No.  127,  Bureau  An. 
Ind.,  U.  S.  Dept.  Agr.) 


Parasitic  in  the  large  intestine,  more  rarely  in  the  small  intestine,  of 
the  sheep  and  goat.  The  species  has  been  collected  in  Europe  and  in  the 
United  States.  It  is  much  less  common  in  this  country  than  (Esophagos- 
tomum  columbianum. 

Occurrence  and  Development. — Nodular  disease  of  the  intestines 
of  sheep  caused  by  (Esophagosotomwn  cohimhianum  is  common  in  the 


284  PARASITES  OF  THE  DOMESTIC  ANIMALS 

United  States.  The  nodules  are  due  to  the  larvae  which  live  embedded  in 
the  connective  tissue  of  the  submocosa,  to  which  they  at  once  penetrate 
after  being  taken  up  by  the  host.  According  to  Marmotel,  after  six  to 
seven  months  of  development  in  this  location,  they  pass  to  the  intes- 
tinal lumen  where  they  become  sexually  mature  and  the  female,  after  cop- 
ulation, deposits  her  eggs.  The  eggs  pass  from  the  host  animal  with  the 
feces  and  promptly  hatch  if  they  meet  with  favorable  conditions  of  heat 
and  moisture.    The  further  development  outside  of  a  host  is  not  known. 

Natural  infection  probably  takes  place  by  food  and  water  from  wet 
marshy  pastures.  If  it  occurs  during  August  and  September  the  larvae 
will  pass  from  the  nodules  into  the  intestinal  lumen  during  March  and 
April,  here  attaining  maturity  and  copulating  in  July  and  August. 

Post-mortem  Appearance. — The  nodules  are  most  commonly  found 
in  the  wall  of  the  cecum  and  colon,  but  they  may  occur  in  the  small 
intestine  and  at  times  on  the  liver  and  other  abdominal  organs.  They 
may  be  isolated,  but  are  frequently  massed  in  hundreds  and  thousands. 
In  size  they  vary  from  that  of  a  pinhead  to  that  of  a  pea,  or  they  maj^ 
be  considerably  larger.  Their  color  varies  from  blackish  in  the  smaller 
ones  to  grayish  white  in  the  larger.  The  connective  tissue  capsule  of 
the  nodule  is  thick,  and,  as  the  nodule  increases  in  size,  it  becomes  filled 
with  a  greenish  cheesy  or  purulent  material,  later  becoming  calcareous. 
Only  the  younger  noclules  contain  the  larvae. 

Symptoms. — Light  infestations,  with  the  presence  of  a  few  nodules, 
are  not,  as  a  rule,  accompanied  by  perceptible  symptoms,  the  condition 
in  such  cases  being  observed  only  after  slaughtering.  Relative  to  their 
degree,  heavier  invasions  may  be  accompanied  by  diarrhea  without  a 
considerable  loss  of  condition,  or  the  diarrhea  may  be  im controllable  and 
accompanied  by  progressive  emaciation  and  anaemia.  Such  cases  usually 
terminate  fatally  after  a  course  of  two  or  three  months,  the  animal 
succumbing  in  a  state  of  coma.  The  effect  of  the  invasion  will  depend 
considerably  upon  the  age  and  vitality  of  the  animals  infested. 

Importance. — The  fact  that  many  slaughtered  sheep  that  were  ap- 
parently perfectly  healthy  show  these  nodules  tends  to  lead  to  the  im- 
pression that  they  are  of  little  importance  and  has  perhaps  caused  them 
to  be  overlooked  as  a  primary  cause  of  death.  Cases  of  nodular  disease 
submitted  to  the  laboratory  of  the  Pennsylvania  Bureau  of  Ani- 
mal Industry  indicate  that  the  disease  may  assume  an  enzootic  char- 
acter of  severe  type  occasioning  numerous  losses.  Usually  where 
there  is  high  mortality  there  is  heavy  infestation  with  large  areas  of 
massed  nodules,  though  there  are  several  factors  which  render  this  un- 
necessary to  a  fatal  termination.  Lighter  invasions  may  have  this 
result  when  by  worms  with  a  relatively  high  degree  of  virulence;  when 
the  invaded  animal  has  a  low  degree  of  resistance,  or  when  other  worms 
are  present  to  contribute  to  the  morbid  effect.     Furthermore,  these 


STRONGYLTX.E  285 

worms  may  infect  the  blood  and  lymph  with  organisms  which  cause 
other  diseases  through  acting  as  direct  carriers  in  penetrating  the  in- 
testinal wall,  or  by  the  wounds  which  they  create  affording  portals  of 
entrance.  In  such  cases  a  comparatively  slight  infestation  with  ffisopha- 
gostomum  would  be  sufficient  for  what  might  prove  a  fatal  secondary 
effect. 

Treatment. — Xo  effective  curative  treatment  is  known.  Preventive 
measures  consist  in  keeping  the  sheep  from  low  wet  areas.  Where  the 
disease  is  prevalent,  lambs  may  be  protected  from  serious  infestation 
by  placing  them  in  a  dry  uncontaminated  lot  and  feeding  and  watering 
them  from  racks  and  troughs  sufficiently  elevated  that  the  contents 
cannot  be  soiled  by  droppings  from  the  nursing  ewes. 

Nodular  Strongylosis  of  Cattle.    Q^soPHAGOsTO\nAsis 

CEsophagostomum  radiatum  «E.  inflatum).  Fig.  151.  Stron- 
g3'linse  (p.  280). — The  thickness  of  the  body  is  nearh' uniform  over  its 
greater  portion;  attenuated  toward  ends.  The  anterior  portion  is 
usually  curved  in  the  form  of  a  hook.  The  cuticular  inflation  about  the 
mouth  (mouth  collar)  is  disk-like,  its  height  a  little  more  than  one- 
fourth  of  its  diameter.  The  mouth  capsule  is  bordered  by  a  circle  of 
numerous  small  triangular  denticles.  The  cervical  groove  and  fold  are 
well  developed  and  the  cuticle  between  it  and  the  mouth  collar  is  in- 
flated. This  inflation  has  a  slight  constriction  at  about  one-third  of  the 
distance  from  the  cervical  groove  to  the  mouth  collar.  The  lateral 
membranes  begin  at  the  cervical  groove  and  extend  well  back  along  the 
bod}^;  near  their  beginning  are  two  cervical  papillae.  The  bursa  of  the 
male  has  two  lateral  lobes  united  by  a  small  median  lobe;  spicules  700- 
800  microns  in  length.  The  vulva  of  the  female  is  transversely  elongated 
upon  an  eminence  located  just  in  front  of  the  anus.  From  the  vulva  the 
body  i-apidly  tapers,  terminating  in  a  tip  which  is  usualh'  somewhat 
bent  in  a  ventral  direction. 

The  female  is  16-20  mm.  (5/8-3/4  of  an  inch)  in  length;  male,  14-16 
mm.  (9/16-5/8  of  an  inch). 

The  eggs  are  oval,  75-80  microns  in  length  by  38-43  microns  in 
breadth.    Their  segmentation  occurs  within  the  body  of  the  female. 

Parasitic  in  the  small  and  large  intestines  of  cattle. 

While  the  nodular  larval  stage  of  CEsophagostomum  columhianum  of 
sheep  is  usually  found  in  the  large  intestine,  that  of  CEsophagostomum 
radiatum  of  cattle  is  often  found  in  the  small  intestine,  the  nodules 
usually  occurring  in  the  terminal  portion  with  involvement  of  the  region 
of  the  ileo-cecal  valve  and  the  cecmu. 

In  other  respects  what  has  been  said  as  to  nodular  disease  of  sheep 
will,  in  its  essentials,  apply  to  that  of  cattle. 


28fi 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Fig.  151. — ffisophagostomum 
radiatum;  male  at  right,  female 
at  left.  *  Vulva.  x5.  (After  Ran- 
som, Bull.  No.  127,  Bureau  An. 
Ind.,  U.  S.  Dept.  Agr.). 


Fig.  152.  —  CEsophagostomum 
radiatum.  Enlarged  anterior  por- 
tion of  bodj%  ventral  view:  c.  a  ., 
annular  groove  surrounding  cervical 
inflation  of  cuticle;  c.  g.,  cervical 
groove;  c.  i.,  cervical  inflation;  c.  p., 
cervical  papilla;  e.  p.,  excretory  pore; 
es.,  esophagus;  int.,  intestine;  1.  m., 
lateral  membrane;  m.  c,  mouth 
collar;  n.  r.,  nerve  ring.  (After  Ran- 
som, Bull.  No.  127,  Bureau  An.  Ind., 
U.  S.  Dept.  Agr.). 


Fig.  153. — ffisophagostomum  radiatum.  Enlarged 
bursa  of  male,  viewed  from  left  side:  d.,  dorsal  ray; 
d.  h.,  dorsal  projection  of  trunk  of  lateral  rays  at  base 
of  postero-lateral  ray;  e.  d.,  externo-dorsal  ray;  e.  1., 
externo-lateral  ray;  1.  t.,  trunk  of  lateral  rays;  1.  v., 
latero-ventral  ray;  m.  1.,  medio-lateral  ray;  p.  1.,  postero- 
lateral ray;  t.  d.,  terminal  branch  of  dorsal  ray;  v.  v., 
ventro-ventral  ray.  (After  Ransom,  Bull.  No  127,  Bu- 
reau An.  Ind.,  U.  S.  Dept.  Agr.). 


STRONGYLIN.E 


287 


Nodular  Stroxgylosis  of  the  Hog.     (Esophagostomiasis 

CEsophagostomum  subulatum  (CE.  dentatum).  Strongylinfie  (p. 
280). — The  body  is  straight  and  attenuated  at  both  (wtreniities.  The 
circular  mouth  is  surrounded  by  a  horny  ring  furnished  with  a  crown  of 
converging  bristles.  Upon  a  cutaneous  ridge  surrounding  the  crown  of 
bristles  are  six  papillae.  There  are  no  lateral  membranes.  The  bursa  of 
the  male  has  two  lateral  lobes  united  by  a  small  median  lobe;  spicules 
slender.  The  vulva  of  the  female  is  just  in  front  of  the  anus  and  is  sur- 
rounded by  a  prominent  ring. 

The  female  is  12-15  nmi.  (1/2-9/16  of  an  inch)  in  length;  male,  8-12 
mm.  (5/16-1/2  an  inch). 

The  eggs  are  oval,  60-80  microns  in  length  by  35-45  microns  in 
breadth. 

This  species  is  found  in  submucous  nodules  and  in  the  lumen  of  the 
large  intestine  of  the  hog.  Considerable  numbers  may  be  present  with- 
out causing  serious  disturb- 
ance. If  the  infestation  is 
unusually  heavy — especially 
if  associated  with  the  thorn- 
headed  worm — there  may  be 
diarrhea,  loss  of  appetite, 
and  general  unthrift.  Such 
cases  may  be  given  treatment 
as  reconnnended  for  other 
roundworms  of  the  intestines 
of  the  hog. 

Strongylosis  of  the  Large 

IXTESTINE     OF    THE    ShEEP 

AND  Goat 

Chabertia  ovina  ( Sclero- 
stomum  hypostomum ) .  Fig. 
154.  Strongylina^  (p.  280).— 
The  body  is  almost  uniform 
in  thickness.  The  head  is 
slightly  globular  and  is  ob- 
liquely ti'uncated  anteriorly, 
the  mouth  facing  antero-ventrally.  The  buccal  capsule  is  large;  l)order 
of  mouth  armed  with  a  double  crown  of  small  triangular  denticles.  Lo- 
cated ventrally,  just  in  front  of  the  excretory  pore,  is  a  short  transverse 
cervical  gi-oove.  The  bursa  of  the  male  is  short  and  has  an  obliquely 
cut-off  appearance;  spicules  long  and  slender.     The  vulva  of  the  female 


Fiu.  1.54. — Chabertia  oviiia;  male  at  right,  female 
at  left.  *  Vulva,  xo.  (After  Ransom,  Bull.  No. 
127,  Bureau  An.  Ind.,  U.  S.  Dept.  Agr.). 


288  PARASITES  OF  THE  DOMESTIC  ANIMALS 

is  situated  a  little  in  front  of  the  anus.  From  in  front  of  the  vulva  the 
body  gradually  attenuates,  the  tail  terminating  behind  the  anus  in  a 
sharply  pointed  tip  which  is  bent  dorsally. 

The  female  is  17-20  mm.  (11/16-3/4  of  an  inch)  in  length;  male,  13- 
14  mm.  (1/2  an  inch). 

The  eggs  are  oval,  90-100  microns  in  length  by  50  microns  in  breadth. 
They  are  segmented  within  the  body  of  the  female.  The  eggs  have 
similar  characters  to  those  of  other  sclerostomes,  and  it  is  probable  that 
the  evolution  external  to  a  host  is  the  same. 

Occurrence. — Strongylosis  of  the  large  intestine  of  sheep  due  to  this 
species  is  probably  more  prevalent  in  Europe  than  in  the  United  States. 
In  reference  to  the  species,  Hutyra  and  Marek  state  that  it  is  often 
found  in  the  colon  of  sheep,  goats,  and  deer,  inducing  in  some  cases 
intestinal  hemorrhage  and  diarrhea  followed  by  anaemia  and  emaciation 
which  may  cause  considerable  loss  among  the  young  animals. 

Neveu-Lemaire  speaks  of  strongylosis  of  the  large  intestine  of  sheep 
as  at  times  ravaging  certain  flocks  in  the  form  of  an  epizootic. 

Ransom,  in  United  States  Bureau  of  Animal  Industry,  Bulletin  No.  127 
(1911),  refers  to  Chahertia  ovina  as  follows:  "This  species  appears  to  be 
comparatively  harmless.  Its  food  consists  of  the  vegetable  material  in 
the  contents  of  the  large  intestine.  The  buccal  capsule  is  commonly 
found  filled  with  such  material." 


Strongylosis  of  the  Intestines  of  the  Horse.     Sclerostomiasis 

1.  Strongylus    equinus    (St.    armatus;    Sclerostomum    equinum). 

Fig.  155.    Strongylinie  (p.  280). — The  body  is  straight,  rigid,  and  finely 

striated  transversely;  color  gray  or  grayish  brown,  or 

^  r\       ^^  ^^^y  ^-*^  shaded  with  red  according  to  the  amount 

i  1/  o    of  ingested  blood.     The  mouth  is  distended  by  several 

chitinous  rings  the  innermost  of  which  are  provided 
with  an  armature  of  fine  teeth,  while  the  outermost 
have  six  papillae.  The  buccal  capsule  has  three  teeth 
at  its  base.  The  bursa  of  the  male  has  two  lateral 
lobes  between  which  is  a  smaller  median  lobe ;  spicules 
long  and  slender.  The  vulva  of  the  female  is  located 
near  the  posterior  third  of  the  body.  The  tail  is  obtuse. 
The  length  of  the  female  varies  from  20-55  mm.  (3/4 
to  2  3/16  inches) ;  that  of  the  male  from  18  to  35  mm. 

T.       1..    ..         (11/16  to  1  3/8  inches). 

Fig.    155— Stron-    ^      '  '  i     „o        •  •      i         -i-i,  i       r  <        • 

gylus  equinus;  male  The  eggs  are  oval,  92  microns  m  length  by  54  mi- 
at  right,  female  at  crons  in  breadth.  Segmentation  commences  at  the 
left,  —  natural  size  ^-         £  ^j    j^.  ^leposition.    The  hatched  embryos  meas- 

(drawn  from    speci-  .  •      i  i 

mens).  ure  340-500  microns  in  length. 


STRONGYLIX.E  289 

2.  Strongylus  edentatus  (Sclerostomum  edentatum).  Strongylinae 
(p.  280).— The  head  is  globular.  The  Ixiccal  capsule  is  goblet-like,  and 
teeth  are  absent.  The  bursa  of  the  male  is  similar  to  that  of  Strongylus 
equinus.    The  vulva  of  the  female  is  near  the  posterior  third  of  the  body. 

The  female  is  33-36  mm.  (1  5/16-1  7  16  inches)  in  length;  male,  23- 
25  mm.  (7/8-1  inch). 

The  eggs  are  oval  and  in  dimensions  about  as  in  Stro7igylus  equinus. 

As  adults  these  worms  are  parasitic  in  the  cecum  and  colon  of  the 
horse;  as  larvie  in  the  abdominal  and  thoracic  organs. 

3.  Strongylus  vulgaris  (Sclerostomum  vulgare).  Strongylinse  (p. 
280). — The  buccal  capsule  is  shallow  and  has  a  single  tooth  at  its  base, 
prominent  projections  causing  the  tooth  to  appear  as  two.  The  bursa 
of  the  male  has  three  lobes,  the  median  one  overlapped  by  the  two 
lateral.    The  vulva  of  the  female  is  near  the  posterior  third  of  the  body. 

The  female  is  24  mm.  (15/16  of  an  inch)  in  length;  male,  15  mm. 
(5/8  of  an  inch). 

The  eggs  are  as  in  the  preceding  species. 

Parasitic  as  adults  in  the  cecum  and  colon  and  in  immature  stages  in 
the  mesenteric  blood  vessels  of  the  horse. 

4.  Cylicostomum  tetracanthum  (Sclerostomum  tetracanthum). 
Strongylime  (p.  280). — A  white  or  reddish  wiiitc  worm,  attenuated 
antcriorl}',  the  mouth  surrounded  l)y  a  cuticular  fold.  The  buccal 
capsule  is  armed  Avith  a  crown  of  triangular  teeth.  The  vulva  of  the 
female  is  just  anterior  to  the  anus. 

The  female  is  10-18  mm.  (3/8-11, 16  of  an  inch)  in  length;  male,  8- 
12  mm.  (5/16-1/2  an  inch). 

The  eggs  are  oval,  100  microns  in  length  by  47  microns  in  breadth. 

Parasitic  in  the  cecum  and  colon  of  the  horse. 

Development. — The  worms  causing  sclerostomiasis  of  the  horse 
were  formerly  grouped  under  the  name  Strongylus  armafiis.  According 
to  Looss  (1902)  it  is  the  innnature  stages  of  the  species  Strongylus  vul- 
garis (Looss,  1900)  which  are  concerned  in  the  production  of  verminous 
aneurysms  in  the  mesenteric  arteries  of  the  horse.  M.  Neveu-Lemaire 
(Parasitologic  des  Animaux  Domestiques,  1912)  describes  the  worm 
responsible  for  these  lesions  under  the  name  Strongylus  equinus. 

This  worm  when  mature  lives  in  the  cecum  and  colon  where  it  firmly 
attaches  to  the  mucosa  by  its  Ijuccal  armature.  In  its  agamous  state  it  is 
found  in  subnuicous  cysts  of  these  organs  and  in  aneurysms  of  the 
mesenteric  artery.  According  to  the  investigations  of  Railliet  the  eggs, 
which  are  deposited  in  the  cecum  and  colon  and  expelled  with  the  feces, 
may  develop  in  a  few  days  if  they  meet  with  moisture  at  a  temperature 
of  12°  to  25°  C.  (53°  to  77°  F.).  The  hatched  embryos,  if  they  continue 
amid  favorable  conditions,  grow,  molt,  and  acquire  a  great  vitality.  It 
is  at  this  stage  that  they  are  ingested  by  the  equine  host  with  the  drink- 


l/ 


290  PARASITES  OF  THE  DOMESTIC  ANIMALS 

ing  water  or  perhaps  with  green  forage.  Reaching  the  intestines,  they 
penetrate  the  mucosa  from  which  probably  the  majority  of  them  reach 
the  circulatory  system  where  the}^  become  lodged  in  the  visceral  arteries, 
as  the  trunk  of  the  great  mesenteric.  After  a  variable  time  in  this 
location  they  again  enter  the  blood  stream  and,  reaching  the  cecum, 
oecome  encysted  in  the  submocosa  where  their  development  proceeds. 
Within  the  cyst  they  possess  a  buccal  capsule  and  a  caudal  bursa,  but 
the  generative  organs  are  not  as  yet  developed. 

Finally  they  pass  to  the  lumen  of  the  bowel  where  they  attach  to  the 
mucosa  and  acquire  all  the  characters  of  the  adult.  Copulation  then 
takes  place,  the  eggs  are  deposited,  and  a  new  generation  repeats  the  cycle. 

Symptoms. — The  symptoms  brought  about  by  the  presence  of  these 
worms — a  condition  generally  known  under  the  name  of  sclerostomiasis — 
are  not  characteristic  and  vary  according  to  the  location  of  the  parasites. 
The  presence  of  the  adults  upon  the  mucosa  of  the  cecum,  even  in  con- 
siderable numbers,  rarely  .causes  serious  disturbance,  diarrhea  and 
occasional  attacks  of  colic  resulting  in  exceptional  cases. 

Sclerostomiasis  produced  by  the  larvae  is  of  a  much  more  serious 
nature.  Their  most  frequent  location  in  this  state  is  in  the  large  arteries 
where  they  bring  about  the  formation  of  verminous  aneurysms,  usually 
at  the  origin  of  the  great  mesenteric.  Fragments  of  the  clot  within  the 
aneurysm  may  be  carried  by  the  blood  to  form  emboli  in  the  arterial 
ramifications  leading  to  the  intestines,  that  portion  of  the  intestine 
supplied  by  an  artery  in  which  an  embolus  is  lodged  being  deprived  of  its 
normal  supply  of  blood.  As  a  result  there  is  suspension  of  secretion  and 
peristaltic  movements  in  this  section,  the  walls  of  a  portion  of  which 
become  dark  and  tumified  with  the  presence  of  hemorrhagic  infarct. 
One  or  more  portions  of  the  intestine  may  be  thus  affected,  the  arrested 
contents  fermenting  and  producing  an  abundance  of  gas,  while  in  the 
healthy  portions  of  the  intestines  there  are  abnormally  energetic  con- 
tractions which  cause  a  severe  enteralgia  and  may  lead  to  invagination, 
displacement,  and  even  rupture.  The  rupture  may  be  of  the  paralyzed 
intestine,  or  it  may  be  of  the  stomach  or  diaphragm,  brought  about  by 
the  accumulation  of  gas  generated  from  the  stagnated  and  fermenting 
intestinal  contents,  the  violent  movements  of  the  animal  often  con- 
tributing toward  this  termination. 

Post-mortem  Appearance. — The  adult  worms  are  fixed  to  the 
mucosa,  usually  that  of  the  cecum,  where  they  nourish  fi-om  the  blood  of 
their  host  and  produce  at  their  point  of  attachment  a  small  dark  prom- 
inence. Immature  worms  may  be  found  in  submucous  nodules  of  the 
cecum,  or  of  both  the  cecum  and  colon.  These  nodules  vary  in  size  from 
that  of  a  pinhead  to  that  of  a  hazelnut  and  contain  a  small  quantity  of 
pus  or  sero-purulent  material  in  which  the  worm,  if  present,  is  rolled  up. 
The  worms  escape  from  the  nodules  by  a  central  orifice  to  the  lumen  of 


STRONGYLIN^  291 

the  intestine  where  they  attach  and  are  sexually  mature,  the  sexes  often 
being  found  coupled  in  this  location.  Before  their  intranodular  existence 
the  larval  worms  live  in  the  blood-vascular  system,  having  gained  this 
location  through  the  intestinal  wall  innnediately  after  their  ingestion. 
It  is  at  this  stage  that  they  produce  the  aneurysms  as  found  in  the  vis- 
ceral trunks  of  the  posterior  aorta.  These  aneurysms  are  usually  some- 
what elongate,  with  tunica  media  much  thickened,  and  with  fibrin 
deposit  upon  the  iiitima,  on  which  a  number  of  reddish  tinted  strongyls 
are  likely  to  be  fixed.  The  aneurysm  may,  however,  be  entirely  free 
from  worms,  in  which  case  they  have  probably  passed  with  the  blood- 
current  to  the  intestinal  wall. 

Where  death  has  occurred  from  thrombo-embolic  colic  due  to  ver- 
minous aneurysm,  the  most  prominent  alterations  found  are  those  which 
have  already  been  described  in  reference  to  this  complication.  The 
intestines  are  usuallj'  much  distended  bj^  gas,  or,  if  rupture  has  occurred, 
this,  with  more  or  less  intestinal  contents,  will  be  in  the  abdominal 
cavity.  Extensive  darkly  discolored  areas  are  usually  observed  in  the 
intestinal  walls,  and  there  are  likely  to  be  evidences  of  degeneration  if 
the  course  of  the  attack  has  been  sufficiently  prolonged.  Owing  to  the 
great  engorgment  of  the  mesenteric  vessels,  it  is  often  difficult,  without 
the  most  searching  examination,  to  discover  the  location  of  the  embolus. 
Rarely  the  immediate  cause  of  death  may  be  found  to  have  been  due  to 
rupture  of  the  aneurysm  and  internal  hemorrhage. 

Treatment. — For  the  strongyles  in  the  intestine  the  same  treatment 
may  be  employed  as  has  been  reconnncnded  for  the  ascarids,  though, 
owing  to  the  firm  attachment  of  the  former  to  the  mucosa,  their  expul- 
sion is  difficult.  Oil  of  turpentine  has  been  recommended  as  particu- 
larly valuable.    It  may  be  given  in  two  to  four  ounce  doses  in  oil. 

In  prophylaxis  clean  water  is  a  main  factor.  This  should  be  filtered  or 
quite  pure  and  free  from  drainage  contamination.  ,  ^^ 


Strongylosis  of  the  Intestine  of  the  Dog  and  Cat. 
Ankylostomiasis 

1.  Ankylostoma  canina  (Dochmius  trigonocephalus;  Uncinaria  tri- 
gonocephala;  U.  canina).  Fig.  156.  8trongylinae  (p.  280). — The  body 
is  whitish  in  color  and  slender;  slightly  enlarged  at  the  anterior  extremity. 
On  the  ventral  surface  of  the  buccal  capsule  are  two  chitinous  plates, 
each  having  three  recurving  teeth.  The  bursa  of  the  male  is  three-lobed, 
two  large  lateral  and  a  small  median.  There  are  two  long  and  slender 
spicules.  The  vulva  of  the  female  is  situated  near  the  posterior  third 
of  the  body. 

The  female  is  10-20  mm.  (3/8-3  4  of  an  inch)  in  length;  male,  9-12 
mm.  (11/32-1/2  an  inch). 


292  PARASITES  OF  THE  DOMESTIC  ANIMALS 

The  eggs  are  oval,  74-84  microns  in  length  bj^  48-54  microns  in 
breadth. 

Parasitic  in  the  small  intestine  of  the  clog  and  cat. 

2.  Uncinaria  stenocephala   (Dochmius  stenocephalus ;   Ankylosto- 
mum  stenocephalum) .      Strongylinse   (p.   280). — The   body  is  very 
slender,  and  the  anterior  extremit}'-  is  much  narrower  than  in  the  pre- 
ceding species,  being  somewhat  attenuated.     The  buccal 
capsule  is  conical  and  has  two  pairs  of  small  teeth  on  the 
ventral  side.    The  bursa  of  the  male  is  similar  to  that  of  the 
preceding  species.    The  vulva  of  the  female  is  situated  near 
y  the  posterior  third  of  the  body. 

Fig.  156—  The  female  is  8-10  mm.  (5/16-3/8  of  an  inch)  in  length; 
Ankylostoma  male,  6-8  mm.  (1/4-5/16  of  an  inch). 

malJ'atHght,       ^^^  ^^gs  are  oval,  63-76  microns  in  length  by  32-38 
female  at  left  microns  in  breadth. 

(drawn  from       Parasitic  in  the  small  intestine  of  the  dog.     There  is  no 
specimens),     authentic  report  of  its  occurrence  in  this  country. 

Occurrence  and  Development. — Ankylostomiasis  (dochmiasis;  un- 
cinariasis) is  a  severe  affection  of  dogs  caused  by  the  presence  of  Ankylo- 
stoma canina.  The  condition  is  analogous  to  ankylostomiasis  or  hook- 
worm chsease  of  man,  caused  by  the  species  Anktjlostoma  duodenale. 

The  worms  fix  themselves  to  the  mucosa  of  the  small  intestine  where 
they  extract  blood.  Hunting  dogs  confined  in  kennels  are  those  which 
most  often  suffer,  especially  if  their  quarters  are  damp.  Cats  are  not 
often  affected. 

The  development  of  the  parasite  is  rapid.  The  eggs  are  segmented 
within  the  body  of  the  female  and,  when  expelled  to  moist  earth,  develop 
embryos  in  three  to  six  days.  These  become  encysted  and,  probably 
through  the  medium  of  contaminated  water,  reach  the  intestine  of  the 
dog  where  they  mature. 

Post-morten  Appearance. — Necropsies  upon  dogs  which  have  died 
in  the  advanced  stages  of  ankylostomiasis  show  the  alterations  of 
anaemia  and  cachexia.  The  mucosa  of  the  small  intestine  is  thickened 
and  marked  by  numerous  hemorrhagic  areas.  Small  ulcerations  are 
present  as  a  result  of  the  irritation  from  the  attachment  of  the  worms, 
and  the  intestinal  contents  may  be  hemorrhagic. 

Symptoms. — The  symptoms  are  those  of  anaemia,  debility,  and 
emaciation.  There  is  depression  and  indifference,  and  hunting  dogs 
lose  their  zest.  The  skin  becomes  dry  and  scaly  and  the  coat  harsh 
and  lusterless.  The  legs  swell  intermittently  at  first,  later  the  edema 
is  greater  in  extent  and  becomes  permanent.  There  is  a  muco-purulent 
discharge  from  the  nostrils  and  this  may  be  streaked  with  blood.  Later 
there  may  be  attacks  of  nasal  hemorrhage.  There  is  at  first  constipation, 
later  a  dysenteric  diarrhea.    Emaciation  and  general  debility  progress, 


STROXGYLIX.E 


293 


and  the  SAnnptoms  are  finalh'  terminated  bj-  death  in  a  state  of  coma  or 
it  may  be  in  conAiilsions. 

Treatment. — As  the  disease  usually  attacks  hunting  packs  in  ken- 
nels, and  there  is  constant  reinfection,  treatment  is,  as  a  rule,  not  suc- 
cessful. It  is  most  important  that  care  be  exercised  as  to  cleanliness  of 
the  kennel.  Where  possible,  the  sick  should  be  removed  to  other  quar- 
ters. Water  and  food  should  be  given  from  buckets  or  troughs  which 
are  thoroughly  flushed  out  after  each  meal,  and  the  j-ards  should  be 
kept  free  from  pools  and  nmd.  As  medicinal  treatment,  the  usual 
vermifuges  reconunended  for  dogs  may  be  tried. 

Other  Strongylinae. — Two  other  strongylines  occasionalh'  found  in 
sheep  and  cattle  may  be  mentioned. 

1.  Bunostomum  trigonocephalum  (Uncinaria  cernua;  Dochmius 
cernuus).  StrongyliniP  (p.  280). — Yellowish  or  reddish  in  color; 
cuticle  transversely  striated.  The 
buccal  capsule  has  a  long  dorsal  tooth 
projecting  forward.  The  mouth  is 
surrounded  by  six  papillae;  cephalic 
extremity  curved  dorsall}-.  The 
vulva  of  the  female  is  near  the  middle 
of  the  body. 

The  female  is  20-28  mm.  (3/4-1  1  '8 
inch)  in  length;  male,  15-18  mm. 
(5/8-11/16  of  an  inch). 

Para.sitic  in  the  small  intestine  of 
rimiinants,  particularh'  sheep  and 
goats. 

2.  Bunostomum  phlebotomum 
(Uncinaria  radiata;  Dochmius  radi- 
atus).  Fig.  157.  Strongylime  (p. 
280).— Dark  in  color.  The  dorsal 
buccal  tooth  is  short;  two  ventral 
buccal  teeth  and  two  subventral 
buccal  teeth  or  lancets.  The  cephalic 
extremity  is  curved. 

The  female  is  24-28  mm.  (15/16-1  1/8  inch)  in  length;  male,  10-16  mm. 
(3/8-5/8  of  an  inch). 
Parasitic  in  the  small  intestine  of  cattle. 


Fig.  157. — Bunostomum  phlebotomum; 
male  at  right,  female  at  left.  *  Vulva. 
x5.  (After  Ransom,  Bull.  No.  127,  Bu- 
reau An.  Ind.,  U.  S.  Dept.  Agr.). 


Teacheal  Strongylosis  of  Chickens.    Syngamosis 


Tm-o  species  of  strongylines  invade  the  trachea  and  bronchi  of  fowl, — 
Syugamus  trachealis  and  Syn.  bronchialis.  The  last  named  is  somewhat 
the  larger  and  inhabits  the  air  passages  of  water  fowl. 


294  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Syngamus.  Strongyliiifie  (p.  280).^ — Members  of  this  genus  have  a 
slender  bod}'  of  reddish  color.  The  month  is  surrounded  by  a  strong 
chitinous  capsule.  The  female  is  much  larger  than  the  male  and  is 
usually  found  with  the  male  firmly  attached  at  the  vulva  which  is  sit- 
uated near  the  anterior  quarter  of  the  body.  This  permanent  coupling 
gives  to  the  pair  a  forked  appearance  from  which  the  worm  has  derived 
its  common  name  of  "forked  worm"  (Fig.  158).  The  attachment  of 
male  and  female  is  less  constant  with  the  species  Syn.  hronchialis. 

The  female  of  Syngamus  trachealis  is  5-20  mm.  (3/16-3/4)  of  an  inch 
in  length;  male,  2-6  mm.  (1/16-1/4  of  an  inch). 

The  eggs  are  elliptical,  measuring  85  microns  in  length  by  50  microns 
in  breadth.  In  the  uterus  of  the  female  they  undergo  a  variable  degree 
of  development,  containing  when  freed  a  segmented  mass  or 
a  developed  embryo.  The  eggs  are  not  laid  but  escape  from 
the  body  by  its  rupture,  which  ordinarily  occurs  from  decom- 
position, though,  according  to  Railliet,  eggs  contained  in 
the  vagina  may  pass  through  the  \ailva  and  from  under  the 
bursa  of  the  male  to  the  outside. 

Occurrence  and  Development. — The  condition  produced 

Fig.   158.  in  fowl  by  syngami  is  commonly  known  in  England  and  the 

—Syngamus  United  States  as  gapes.     It  is  widely  prevalent,  practically 

male     (at-  all  of  our  domestic  birds  and  many  wild  birds,  especially 

tached      at  those  in  captivity,  suffering  from  it. 

malef "  ^^'  ^  peculiar  feature  in  the  evolution  of  Syngamus  trachealis 
is  the  fact  already  noted  that,  due  to  the  covering  of  the 
vulva  by  the  permanent  attachment  of  the  male,  the  eggs  cannot  be 
extruded  and  are  only  liberated  by  the  rupture  or  disintegration  of  the 
mother  worm.  This  may  occur  within  the  air  passages  or  after  the 
worm  has  been  expelled.  If  the  eggs  meet  with  water  or  moist  earth 
the  embryos  develop  and  are  hatched  in  seven  to  forty  da3'S  according 
to  temperature.  Birds  may  become  infested  by  ingesting  eggs  or  em- 
bryos, often  by  eating  the  worms  expelled  by  infested  members  of  the 
flock.  From  the  digestive  tract  the  larvse  migrate  to  the  air  passages 
where  they  mature. 

Lesions. — The  worms  are  generally  found  covered  with  mucus  and 
in  greatest  number  near  the  division  of  the  trachea  into  bronchi.  The 
mucosa,  to  which  they  are  firmly  fixed  by  their  buccal  capsule,  exhibits 
at  each  point  of  attachment  a  small  purulent  tumor,  or  there  may  have 
developed  an  abscess  sufficiently  large  to  obstruct  the  trachea.  The 
number  of  coupled  worms  present  may  be  three  or  four  or  twenty  to 
thirt}'-,  the  smaller  numbers  being  quite  sufficient  to  cause  death  by 
asphyxiation,  though  this  will  be  influenced  somewhat  by  age  and  the 
diameter  of  the  trachea. 

Symptoms. — Young  birds  suffer  most  from  syngamosis,  those  in 


STRONGYLIX.E  295 

good  condition  being  equally  susceptible  with  others.  A  typical  symp- 
tom of  the  affection  is  a  peculiar  stretching  of  the  neck  accompanied 
by  a  yawn-like  opening  of  the  beak  from  which  movement  the  disease 
derives  its  name  "gapes."  The  birds  repeatedly  shake  their  heads, 
sneeze,  and  expel  tenacious  masses  of  mucus  which  may  contain  one 
or  more  pairs  of  the  worms.  The  appetite,  at  first  voracious,  diminishes, 
and  the  birds  become  dull  and  inactive  with  feathers  erect  and  lusterless. 

Emaciation  progresses,  the  mouth  is  filled  with  frothy  saliva,  respira- 
tion becomes  increasingly  difficult,  and  the  animal  dies  from  exhaustion, 
or  it  raaj'  be  from  asphyxia  before  such  advanced  symptoms  are  reached. 
Recovery  is  rare  in  young  l)irds.  Older  ones  sometimes  survive  if  the 
infestation  is  light. 

Treatment. — A  method  of  treatment  commonh'  practiced  is  to  strip 
a  feather  of  its  barbules  to  within  a  short  distance  of  its  tip  and  inserting 
this  into  the  trachea  with  a  rotary  movement,  attempt  to  detach  and 
elevate  the  worms.  Only  such  worms  as  are  not  firmly  fixed  to  the 
mucosa  are  removed  by  this  process  and,  in  view  of  the  danger  of  its 
causing  suffocation,  it  is  a  questiona])le  procedure  unless  as  an  urgent 
palliative  measure. 

A  better  treatment  is  to  give  with  the  food  certain  substances  of  strong 
odor  eliminated  in  the  respiratory  passages  and  having  a  deleterious 
effect  upon  the  parasites.  As  such  agents  garlic  and  asafetida  have 
been  employed  with  success.  According  to  Neumann,  Megnin  has  had 
good  results  with  a  mixture  of  equal  parts  of  asafetida  and  powdered 
gentian  root  incorporated  in  a  cake  and  given  in  the  proportion  of  eight 
grains  per  bird  each  day. 

Another  method  reconnnended  is  the  injection  into  the  trachea  of 
about  fifteen  drops  of  a  five  to  eight  per  cent,  solution  of  salicylic  acid. 
The  injection  should  be  made  slowly  with  a  small  syringe  and  canula. 

Fumigations  with  such  agents  as  sulphurous  acid  or  tobacco  smoke, 
resorted  to  by  some,  involve  such  risk  of  accident  from  suffocation  as 
to  make  their  use  unadvisable. 

As  prevention,  affected  birds  and  those  apparently  health}-  should 
be  removed  to  clean  and  separate  quarters  and  the  infested  yards 
cleaned  and  sprinkled  with  a  one  to  one  thousand  solution  of  sulphuric 
acid.  The  bodies  of  dead  birds  are  to  be  buried  deeph'  or  burned. 
Food  and  water  should  be  fresh,  given  from  clean  utensils,  and  not  per- 
mitted to  stand  about.  As  an  aid  in  prevention  the  addition  of  fifteen 
grains  of  salicylate  of  soda  to  the  quart  of  drinking  water  has  been 
recommended. 

The  Kidney  \\'orm  of  the  Hog 

Stephanurus  dentatus.  StrongyHdse  (p.  255). — This  worm  is  at 
present  of  somewhat  uncertain  position  in  the  classification  of  the 


296  PARASITES  OF  THE  DOMESTIC  ANIMALS 

strong3des.  The  body  is  thick,  cyHndrical,  and  has  a  mottled  appear- 
ance, due  to  the  intestine  and  reproductive  organs  showing  through 
the  semi-transparent  integument.  Both  extremities  are  somewhat 
blunted;  the  mouth  terminal  with  six  small  teeth.  The  bursa  of  the  male 
is  formed  of  five  tongue-like  parts  united  by  a  membrane;  there  is  but 
one  spicule.  The  obtuse  caudal  extremity  of  the  female  is  curved; 
^^ilva  near  the  middle  of  the  body. 

The  length  of  the  female  is  30-40  mm.  (1  3/16-1  9/16  inch);  male, 
22-30  mm.  (7/8-1  3/16  inch). 

Parasitic  in  fat  surrounding  abdominal  viscera,  especially  that  of  the 
sublumbar  region  in  the  vicinitj^  of  the  kidneys. 

The  kidney-worm  is  found  in  hogs  of  the  United  States — especially 
those  of  the  South — and  in  South  America,  the  species  being  first  dis- 
covered in  Brazil.  Its  presence  may  cause  the  formation  of  cysts  up 
to  the  size  of  a  pigeon's  egg  in  the  adipose  tissue,  these  on  incision  usually 
revealing  one  or  two  of  the  worms  and  a  small  amount  of  pus.  Rarely 
the  worms  penetrate  the  capsule  of  the  kidney  or  enter  the  suprarenals. 
Indurated  fistulous  tracts,  liver  lesions,  and  peritoneal  effusion  have 
been  observed  as  a  result  of  the  presence  of  these  parasites,  though  it 
may  be  said  of  them  that  they  rarely  cause  perceptible  disturbance 
unless  in  unusual  locations  in  the  abdominal  cavity. 

Due  to  their  location,  treatment  can  be  of  no  value. 


FAMILY  VL    EUSTRONGYLID.E 

EUSTRONGYLOSIS 

This  is  a  condition  produced  by  a  giant  nematode, — Diocioplujme 
renale  (D.  visceralis;  Eustrongylus  visceralis;  Eu.  gigas),  which  is  some- 
times met  with  in  the  kidney  and  peritoneal  cavity  of  dogs  and  other 
domestic  animals.    It  has  also  been  reported  in  man. 

Diodophyme  r-enale  (Nematoda,  p.  217)  is  of  somewhat  uncertain 
position  among  the  nematodes.  It  has  been  commonly  placed  with  the 
family  Strongylidae,  but  it  does  not  conform  to  all  of  the  characteristics 
of  this  family.  Neveu-Lemaire  describes  the  genus  Eustrongylus  under 
the  separate  family  Eustrongylidse. 

The  worm  is  the  largest  of  all  the  nematodes,  the  female  attaining 
a  length  of  one  meter  (39  inches)  and  a  thickness  of  a  centimeter  (3/8 
of  an  inch);  the  males  a  length  of  forty  centimeters  (15  inches).  The 
body  is  blood-red  in  color,  somewhat  thinner  toward  the  anterior  ex- 
tremity than  posteriorly.  The  bursa  of  the  male  is  collar-like,  entire, 
and  without  rays.  Within  its  base  is  located  the  anus.  There  is  a  single 
slender  spicule  (Fig.  159).  The  tail  of  the  female  is  obtuse.  There  is  a 
single  ovary;  vulva  near  the  mouth. 


EUSTRONGYLID^ 


297 


The  eggs  are  64-68  microns  in  length  by  40-44  microns  in  width. 
They  are  brownish  in  color  and  have  numerous  round  depressions  on 
their  surface.    The}^  develop  in  a  moist  medium. 

The  embryos  are  tapering  at  the  extremities  and  about  240  microns 
in  length  by  40  microns  in  breadth.    They  have  a 
great  vitalitj^  and  may  survive  within  the  eggs  for 
a  year  or  more. 

Attempts  at  direct  infection  have  been  unsuc- 
cessful. An  intermediate  host  is  evidently  re- 
quired, and  the  fact  that  the  worm  is  found  para- 
sitic in  the  seal  and  otter  points  to  the  probability 
that  it  lives  a  portion  of  its  life  in  a  fish. 

The  eustrongyle  is  much  more  frequent  in  Car- 
nivora,  especially  the  dog,  than  in  other  animals, 
but  it  is  rareh'  met  with.  In  the  Journal  of  the 
American  Veterinary  Medical  Association,  June, 
1917,  Hall  states  that  from  Riley's  and  his  own 
record  of  cases  reported  it  appears  that  this  worm 
has  been  found  at  least  forty  or  fifty  times  in  the 
United  States.  How  and  in  what  form  it  finds  its 
wa}^  into  the  body  of  its  host  is  not  known.  It  is 
most  frequentl}^  found  in  the  pelvis  of  the  kidney 
where  it  grows  to  an  enormous  size,  producing  a 
purulent  inflammation  from  which  destruction  of 
the  renal  tissue  follows.  Eventually  the  kidney 
becomes  a  mere  thick-walled  cyst  containing  a 
bloody  purulent  material  within  which  the  worm 
is  coiled  up.  But  one  kidney  is  invaded,  usually- 
by  a  single  worm,  though  in  rare  cases  two  have 
been  found  in  the  kidney  pelvis.  The  uninfestcd 
kidney  is  usually  found  to  have  undergone  a  com- 
pensatory hypertrophy.  The  worm  has  been 
met  with  in  other  parts  of  the  urinary  organs,  as 
in  a  part  or  the  whole  of  the  lu'eter  and  in  the 
bladder.  Where  it  is  found  outside  of  the  urinary 
organs,  as  in  the  peritoneal  cavity',  it  is  probable 
that  it  did  not  reach  such  location  until  after 
primary  development  in  the  urinary  passages. 

Symptoms. — The  symptoms  are  not  characteristic  and  in  some  cases 
may  not  be  observed.  Horses  and  cattle  especially  are  said  to  show 
little  disturbance  from  the  presence  of  the  worm,  while  dogs,  on  the 
other  hand,  suffer  severe  pain,  are  restless,  and  sometimes  exhibit  a 
lateral  curvature  of  the  vertebral  column,  the  concavity  corresponding 
to  the  affected  side.    ^Nlicturation  may  be  painful  and  with  effort,  and 


Fig.  1.59.— Diocto- 
phyme    renale;    male, — 
natural  size  (after  Rail- 
liet). 


298  PARASITES  OF  THE  DOMESTIC  ANIMALS 

the  urine  may  be  purulent  and  bloody.  An  exact  diagnosis  can  only 
be  made  in  the  living  animal  by  finding  the  characteristic  eggs  of  the 
eustrongyle  in  the  urine. 

In  view  of  the  location  and  size  of  the  worm,  treatment  is  imprac- 
ticable. 


chapter  xxiv 
xe:\iatoda.  family  vii.  trichixellid.e 

Xematoda  (p.  217j. 

The  nematodes  of  this  faniil}'  have  a  very  slender  and  elongated 
anterior  portion  of  the  body,  containing  only  the  esophagus.  The  pos- 
terior portion  is  more  or  less  enlarged  and  is  occupied  h)y  the  intestine 
and  reproductive  organs.  The  mouth  is  rounded  and  nude.  The  anus 
is  terminal  or  nearly  so.  The  males  have  a  single  testis  and  but  one 
spicule  or  the  spicule  may  be  absent.  The  females  have  a  single  ovary. 
The  vulva  is  located  at  the  junction  of  the  smaller  with  the  larger  por- 
tion of  the  bodj'.  They  are  oviparous  (Trichuris)  or  ovoviviparous 
(Trichinella). 

The  worms  of  this  group  to  be  described  come  under  two  genera, — 
Trichuris  and  Trichinella.  Of  those  but  one  species, — Trichinella 
spiralis,  is  of  pathologic  importance. 

Trichuris  ovis  fTrichocephalus  affinisj.  Fig.  IGO.  Trichinelhdse 
(p.  299). — The  esophageal  portion  of  the  body  is  very  long  and  slender; 
the  posterior  portion,  containing  the  reproductive  organs,  much  thicker. 
The  head  is  sometimes  provided  with  two  transparent  wing-like  en- 
largements. The  posterior  extremity  is  more  or  less  blunt  and  rounded. 
The  body  is  transversely  striated.  The  posterior  portion  of  the  body 
of  the  male  is  rolled  dorsally  in  a  spiral.  The  spicule  is  verj-  long, 
measuring  5-7  mm.  (7/32-9/32  of  an  inch)  and  terminating  in  a  sharp 
point. 

The  female  is  50-70  mm.  (2-2  3/4  inches)  in  length,  the  esophageal 
portion  constituting  about  two-thirds  of  the  total  length.  The  male  is 
50-80  mm.  (2-3  1/8  inches)  in  length,  the  esophageal  portion  in  the 
same  proportion  to  the  total  length  as  in  the  female. 

The  eggs  are  lemon-.shaped,  70-80  microns  long,  and  have  an  opercular 
plug  at  each  end.    Development  is  direct. 

This  species  is  a  common  para.site  in  the  large  intestine  of  ruminants, 
particularly  the  sheep  and  goat.  Leuckart  has  demonstrated  that  it 
develops  directly  from  the  egg  without  intermediate  host  and  without 
a  free  hving  stage.  When  the  eggs  are  taken  into  the  intestine  of  the 
nmiinant  host  the  embr>'OS  are  freed  and  attain  their  adult  development 
in  about  sixteen  daj's.  They  are  usually  found  attached  firmly  to  the 
mucosa,  but  apparently  cause  littlo  if  any  trouble. 

Trichuris  crenatus  '  Trichocephalus  crenatus).  Trichinellidae  (p. 
299). — The  esophageal  portion  of  the  body  is  very  slender,  the  posterior 


300 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


Fig.  Itil. — Trichuris  ovis.  Egg. 
x600.  (After  Ransom,  Bull.  No.  127, 
Bureau  An.  Ind.,  U.  S.  Dept.  Agr.). 


Fig.  160, 
at  left.     *  Vulva,    xo 
tice,    Bull.    No.    127, 
Dept.  Agr.). 


portion  enlarged.  The  female 
measures  35-50  mm.  (1  3/8-2 
inches)  in  length,  the  anterior 
slender  portion  constituting 
about  two-thirds  of  the  total 
length.  The  length  of  the  male 
is  33-40  mm.  (1  5/16-1  9/16 
inch),  the  anterior  part  about 
five-eighths  of  the  total. 

The  eggs  are  52-56  microns 
in  length. 

The  worm  lives  in  the  large 
intestine  of  domestic  and  wild 
hogs.  Infestation  occurs  as  in 
the  preceding  species.  Ap- 
parently little  disturbance  is 
caused  by  its  presence. 

Trichuris  depressiusculus 
( Trichocephalus  depressiuscu- 
lus). Trichinellidse  (p.  299).— 
The  male  and  female  are  45- 
75  mm.  (1  3y^4-3  inches)  in 
length,  the  slender  esophageal 
portion  constituting  the  ante- 
Trichuris  ovis;  male  at  right,  female  rior  three-quarters.     The  spe- 


(After  Ransom,  from  Cur- 
Bureau    An.    Ind.,    U.  S. 


cies  resembles  Trichuris  ovis  of 
ruminants  and  Tr.  dispar  of 
man.     The  spicule  of  the  male 

may  reach  the  length  of  10  mm.  (3/8  of  an  inch)  and  terminates  in  a 

sharp  point. 

The  eggs  are  70-80  microns  in  length.     The  development  is  similar 

to  that  of  the  preceding  species. 

This  parasite  inhabits  the  large  intestine,  usually  the  cecum,  of  the 

dog.    Eggs  taken  up  by  dogs  release  their  embryos  within  the  digestive 

tract  where  they  attain  full  development.     The  worms  are  often  found 


TRICHINELLID^ 


301 


in  the  cecum  of  clogs  suffering  from  ankylostomiasis,  but  have  an  in- 
significant secondary  part  to  Ankylostoma  canina  as  a  cause  of  this 
affection. 

Trichinosis 

Trichinella  spiralis  (Trichina  spiralis).  Fig.  162.  Trichinelhdse 
(p.  299). — A  veiy  small  worm  with  bod}'  somewhat  thicker  posteriorly, 
but  without  abruptly  demarcated  fila-  g 

mentous  anterior  as  in  the  Trichurinae. 
The  mouth  is  round  and  unarmed.  The 
esophageal  portion  extends  to  about  one- 
half  of  the  length  of  the  body,  the  esoph- 
agus embedded  in  a  chain  of  single  cells. 
The  portion  of  the  body  posterior  to  the 
esophageal  contains  the  intestine  which 
ends  in  a  terminal  anus.  The  single 
testis  of  the  male  originates  posteriorly- 
and  extends  forward  to  the  esophagus 
where  it  turns  back  and  becomes  the 
seminal  vesicle  which  terminates  at  the 
anal  aperture.  The  cloaca  thus  formed 
has  on  each  side  of  its  opening  two  pro- 
jections which  serve  to  clasp  the  female, 
the  cloaca  being  extmded  in  copulation. 
There  is  no  spicule.  The  single  ovary 
of  the  female  begins  posteriorly  and,  ex- 
tending forward  for  a  short  distance,  be- 
comes the  uterus.  The  vulva  is  about 
one-fifth  of  the  length  of  the  body  from 
the  anterior  end. 

The  female  is  3-4  mm.  (1/8-5/32  of  an 
inch)  in  length;  male,  1.4-1.6  mm.  (1/16 
of  an  inch). 

The  embrs^os  are  developed  within  the 
uterus  and  are  hatched  there  by  breaking 
through  the  delicate  membrane  sur- 
rounding the  egg.  From  the  uterus  and 
vagina  they  pass  from  the  bod}'  of  the 
mother  worm  through  the  vulva.  The 
hatched  embryos  are  100-160  microns 
long  by  9  microns  thick,  the  anterior  end 
somewhat  thicker  than  the  posterior. 

Parasitic  as  adults  in  the  small  intestine  and  as  larvae  in  the  muscula 
ture  of  hogs,  rats,  mice,  and  other  mammals,  including  man. 


Fig.  162. — Trichinella  spiralis; 
male  at  left,  female  at  right, — 
much  enlarged. 


30^ 


PARASITES  OF  THE  DOMESTIC  AXi:\L\LS 


Life  History. — When  flesh  containing  encapsulated  living  trichinae 
is  taken  into  the  stomach  of  a  suitable  animal,  the  capsule  is  digested 
and  they  are  liberated  within  eighteen  to  twenty-four  hours.  The 
larvae  then  enter  the  small  intestine  and  are  sexually  mature  in  two  to 
five  daj-s.  The  females  with  the  males  are  pressed  into  the  crypts  of 
Lieberkijhn  where,  a  week  to  ten  days  after  the  infection,  the  female 
deposits  living  embryos.  There  is  at  first  an  equal  number  of  males 
and  females  in  the  intestine;  later  the  males  gradually  disappear,  so 
that  ten  to  fourteen  daj's  after  infection  almost  all  of  the  worms  will  be 
females.  These  live  five  to  eight  weeks,  a  single  female,  according  to 
Leuckart,  depositing  not  less  than  fifteen  hundred  embryos;  according 
to  Braun,  the  nmnber  may  reach  ten  thousand. 

From  Lieberktihn's  glands  the  embryos  penetrate  the  mucosa  and, 
reaching  the  lymphatics,  are  probably  carried  to  the  blood  by  wa}^  of 
the  thoracic  duct.  With  the  blood  they  are  distributed  to  various  parts 
of  the  body,  passively  in  greater  part,  though  it  is 
probable  that  their  ultimate  lodgment  is  influenced 
somewhat  by  their  activity.  Embryos  deposited  by 
capillary  blood  in  striated  muscle  with  sarcolemma 
are  amid  conditions  favorable  to  their  further  develop- 
ment. From  the  capillaries  the  trichinae  force  their 
way  through  the  sarcolemma  and  into  the  plasma  of 
the  muscle-fiber,  where,  at  first  actively  motile,  they 
pass  to  a  state  of  rest  and  proceed  to  develop  into 
the  larval  stage  at  which,  if  ingested,  they  may  infect 
other  animals. 

In  about  three  weeks  after  the  occurrence  of  the 
infection  the  larvae  in  their  muscular  location  have 
attained  a  length  of  eight-tenths  to  one  millimeter, 
and  their  growth  is  completed.  At  this  time  they 
are  usual Ij'  curved  in  the  form  of  a  sickle,  later  becom- 
ing coiled  spirally  (Fig.  163),  from  which  characteristic 
they  derive  their  specific  name,  though  they  may  be 
found  in  various  looped  and  curved  forms.  The  an- 
terior portion  of  the  larva  is  now  the  thinner;  the  pos- 
terior thicker  and  rounded  at  its  extremity. 
As  a  result  of  this  invasion  the  muscle-fibers  undergo  certain  changes; 
the  transverse  striation  is  lost,  there  is  degeneration  of  the  sarcoplasm, 
and  the  nuclei  increase  in  number  and  size,  each  becoming  surrounded 
by  a  granular  mass.  The  irritation  to  the  surrounding  tissues  caused 
by  the  presence  of  the  parasites  results  in  the  formation  of  cysts  which 
enclose  the  trichinae  and  are  fulh'  developed  at  the  end  of  the  thu'd 
month.  The  long  axis  of  the  capsule  is  parallel  to  that  of  the  muscle- 
fiber.    The  capsules  are  usually  oval  in  shape  and  more  or  less  drawn 


Fig.  163.— Tri- 
chinella  spiralis. 
Encysted  larva  in 
muscle  (after  Leuc- 
kart). 


TRICHINELLID^  303 

out  at  the  i^oles,  giving  them  somewhat  the  shape  of  a  lemon.  Their 
dimensions  vaiy  with  the  thickness  of  their  walls.  In  general,  they 
are  about  four-tenths  of  a  millimeter  in  length  by  twenty-five  one- 
hundredths  of  a  millimeter  in  })readth,  but  their  length  may  be  from 
three-tenths  to  eight-tenths  of  a  millimeter  and  their  breadth  from 
two-tenths  to  four-tenths  of  a  millimeter.  After  the  formation  of  the 
cysts  they  are  often  made  more  recognizable  to  the  unaided  eye  by  the 
deposition  of  fat  cells  innnediately  around  their  poles.  Within  each 
cyst  there  is  usuallj-  one,  more  rarely  two  or  more,  larva?. 

Tabular  Review  of  Life  History  of  Trichinella  Spiralis 

Mature  Womis. — In  intestines  of  hog,  rat,  etc.    Period  of 
I  intestinal  trichinosis. 

Embrvos. — In  intestinal  crvpts  of  same. 

Embryos. — In  lymph  and  blood  currents  after  pene- 

I  trating  intestinal  wall. 

Embryos. — ]\Iigrating  within  fibers  of  voluntary  mus- 

I  cle.    Period  of  muscular  trichinosis. 

Encysted  Larvae. — ^At    rest   within   voluntary    muscle- 

I  fibers. 

Larvae. — Freed  from  C3^sts  after  ingestion  by  hog,  rat, 

I  man,  etc. 

Mature  Worms. — In  intestines  of  same. 

Degeneration. — After  a  varj-ing  jx'riod  of  time  the  trichina  cyst 
undergoes  fatty  and  calcareous  degeneration.  In  the  first  there  api)ear 
within  the  cyst  cells  small  fat  granules  which  rapidly  increase  in  number 
and  are  soon  set  free  to  invade  the  whole  of  the  C3'st.  Later  there  is  a 
deposition  of  carbonate  and  phosphate  of  lime,  the  calcification  involving 
the  capsule  and  the  tissues  of  the  trichina,  though  the  latter  often  es- 
capes the  process,  and  perfectly  intact  trichinae  ma}'  be  found  in  cysts 
entirely  calcified  and  opaque. 

Calcification  of  the  capsule  begins  about  the  seventh  month  after  in- 
fection and  is  completed  in  from  fifteen  to  eighteen  months,  though  ex- 
ceptions give  to  these  periods  but  a  general  application.  Ostertag 
states  that  completely  calcified  trichina  capsules  were  found  in  two 
hogs  nine  and  twelve  months  old,  and,  according  to  the  same  author, 
Dammann  reported  a  case  in  which  after  eleven  years  the  trichina  cap- 
sules were  not  completely  calcified  and  contained  trichina  still  capable 
of  producing  experimental  trichinosis. 

Location. — Encysted  trichinae  are  found  in  striated  muscle  in  which 
the  fibers  have  a  sarcolemma.     Thev  are  not  found  in  the  muscle- 


304  PARASITES  OF  THE  DOMESTIC  ANIMALS 

fibers  of  the  heart.  Certam  muscles  are  pecuharly  liable  to  invasion 
by  the  parasites,  and  these  in  the  order  of  frequency  may  be  listed  as 
follows, — pillars  of  the  diaphragm,  muscles  of  the  larynx  and  tongue, 
abdominal  and  intercostal  muscles,  psoas  muscles,  and  muscles  of  the 
back.  They  are  usually  found  in  greatest  number  toward  the  extrem- 
ities of  the  muscles  in  the  neighborhood  of  tendons,  a  fact  probabh'  to 
be  accounted  for  in  the  arrest  offered  by  these  locations  to  their  migra- 
tions. 

The  nmuber  of  cysts  which  an  infested  individual  may  harbor  is 

capable  of  reaching  an  enormously  high  figure.    Neumann  states  that 

Leuckart  has  counted  between  twelve  hundred  and  fifteen  hundred  in  a 

gram   (15.43  grains)   of  muscle,  while  Fielder, 

jJBHIIjjHj    according  to  the  same  author,  estimated  the 

^^^^B^^^H    number  found  in  the  body  of  a  young  woman 

^^HflH^^^S    as  ninety-four  million. 

l^^^^^^^^B^  Occurrence. — Adult  trichinae  are  only  found 
J^^H^^^^^  in  the  intestines,  especially  the  upper  part  of 
^^i^H^^l^J^^JI  the  small  intestine,  of  mammals  and  birds  which 
^^^  Wm^  have  recently-  eaten  flesh  containing  the  en- 
^       I    cysted  larva?.    In  fishes  and  other  cold-blooded 


Fig.  164.  —  Trichinella  vertebrates  the  trichina  cysts  are  not  acted 
spiralis.    Cyst   in    human  ^jpon  by  the    digestive  canal  and    thev  pass 

muscle      (from      micropho-     . ,  i         • ,  i         ,      i  r^t-  l^  •        i" 

tograph  by  Hoedt).  through  Without  change.     Ui  the  animals  com- 

monly used  for  human  food  only  the  hog  harbors 
muscle  trichinae  by  natural  infection,  and  trichinosis  of  man  is  usually 
acquired  by  eating  the  trichinosed  flesh  of  this  animal.  Rats  are  peculiarly 
susceptible  to  trichina,  and  probably  one  of  the  most  frequent  sources 
of  the  infection  of  hogs  is  by  eating  trichinous  rats.  Transmission  to 
herbivorous  animals,  as  cattle,  sheep,  and  horses,  is  difficult.  After 
experimental  feeding  of  flesh  containing  the  cysts  to  these  animals 
there  is  usually  a  development  of  intestinal  trichinae  but  no  muscle 
trichinae.  Intestinal  trichinae  have  been  experimentalh^  developed  in 
birds,  but  birds  do  not  harbor  the  encysted  larvae. 

Only  encysted  living  larvae  are  capable  of  producing  trichinosis  in 
their  suitable  hosts.  Ingested  larvae  which  are  unprotected  b}^  a  cyst 
are  destroyed  in  the  stomach  by  the  direct  action  of  the  gastric  juice. 

Symptoms  in  Hogs. — Sj'mptoms  of  trichinosis  by  natural  infection 
are  rarely  observed  in  hogs,  though  where  a  considerable  quantity  of 
the  cysts  have  been  ingested  it  is  probable  that  such  s\anptoms  follow, 
their  true  cause  being  unrecognized.  Feeding  experiments  have  shown 
that  after  massive  infestation  intestinal  trichinosis  is  manifested  by 
the  third  to  the  eighth  day.  There  is  then  depression,  loss  of  appetite, 
grinding  of  the  teeth,  and  a  disposition  to  remain  crouched  in  the 
bedding  or  to  stand  about  with  back  arched  and  abdomen  retracted. 


TRICHIXELLID.E  305 

A  persistent  diarrhea  follows  whicli  is  at  first  liunp\-,  then  watery  and 
of  bad  odor.  With  these  symptoms  there  may  also  be  those  of  colic. 
In  general  the  symptoms  are  those  of  an  entero-peritonitis  and  they 
continue  over  several  weeks  during  which  time  the  animal  may  die. 

In  from  one  to  two  weeks  the  larvae  are  penetrating  the  muscular 
tissue,  and  muscular  trichinosis  has  set  in.  The  animal  now  lies  upon  its 
side,  or,  if  it  moves  about,  it  is  in  a  stiff,  halting,  and  painful  manner. 
The  respiration  is  superficial,  the  voice  husky,  and  chewing  and  swallow- 
ing difficult. 

With  the  coming  to  rest  and  encapsulation  of  the  larvie  the  animals, 
in  most  cases,  gradually'  recover.  Where  there  has  been  exceptionally 
heavy  infestation  edema  may  appear  in  various  parts  of  the  body; 
such  a  development  is  usually  followed  by  death. 

Prophylaxis. — IVIost  all  cases  of  infection  of  man  with  trichina  are 
from  eating  trichinosed  pork,  the  swine  usually  becoming  infected  by 
eating  the  trichinous  flesh  of  other  swine  or  that  of  affected  rats  and 
mice.  Knowing  these  facts,  prevention  is  made  relatively  simple. 
Places  where  hogs  are  kept  should  be  freed  from  rats,  and  the  flesh  of 
animals  subject  to  nuiscular  trichinosis  should  not  be  fed  to  hogs  un- 
less it  has  been  thoroughh-  cooked.  According  to  Leuckart,  trichinae 
are  killed  at  a  temperature  between  62°  and  70°  C.  (143°-158°  F.). 
These  degrees  of  heat  nuist  be  continued  sufficiently  to  penetrate  the 
entire  piece  of  meat,  a  white  or  light  gray  cut  surface  indicating  that  the 
cooking  has  been  sufficient. 

Treatment.— Treatment  is  ineffectual.  In  the  case  of  such  an  ex- 
tremely rare  occurrence  as  the  early  diagnosis  of  intestinal  trichinosis, 
the  administration  of  anthelmintics  followed  ])y  purgatives  might  be 
of  some  value,  but  the  deep  location  of  the  mature  worms  in  the  crypts 
of  the  mucosa  affords  them  a  high  degree  of  protection  against  such 
agents. 


CHAPTER  XXV 

THE  THORN-HEADED  WORM.    THE  LEECHES 

Order  II.  Acanthocephala.  Nemathelminthes  (p.  216). — Essential 
differences  separating  this  order  from  the  Nematoda  are  the  absence  of 
a  digestive  tube  and  the  possession  of  a  protractile  rostrum  provided 
with  hooks.  The  body  cavity  contains  a  fluid  in  which  are  the  sexual 
organs.    The  sexes  are  separate. 

One  species  is  of  suflficient  pathologic  importance  for  consideration. 
This  is  the  large  intestinal  roundworm  of  the  hog,  Gigantorhynchus 
hirndinaceus  of  the  family  Gigantorhynchidge,  more  commonly  described 
under  the  name  Echinorhynchus  gigas. 

Gigantorhynchus  hirudinaceus  (Echinorhynchus  gigas).  Fig.  165. 
Acanthocephala  (]3.  306). — The  body  is  white,  cylindrical,  transversely 
wrinkled,  and  often  expanded  at  several  points.  The  rostrum  is  almost 
globular,  retractile,  and  has  five  or  six  rows  of  backward-curving  hooks 
(Fig.  166).  The  caudal  extremity  is  somewhat  tapering.  The  males 
are  smaller  and  thinner  than  the  females  and  have  a  bell-shaped  caudal 
bursa.    The  caudal  extremity  of  the  female  is  rounded. 

The  female  is  20-35  cm.  (8-13  inches)  in  length  by  4-9  mm.  (5/32- 
11/32  of  an  inch)  in  breadth.  The  male  is  6-10  cm.  (2  3/8-4  inches)  in 
length  and  in  breadth  3-5  mm.  (1/8-7/32  of  an  inch). 

The  eggs  are  oblong,  measuring  87-100  microns.  When  developed 
they  are  surrounded  by  three  envelops.  The  embryos  are  formed  within 
the  body  of  the  female. 

The  adult  worm  is  parasitic  in  the  small  intestine  of  the  hog;  excep- 
tionally it  occurs  in  man.  The  larva  lives  encA'sted  in  the  white  grub 
of  the  May-beetle  and  probably  some  other  invertebrates. 

The  eggs  of  Gigantorhynchus,  discharged  to  the  ground  with  the 
feces  of  the  hog  and  eaten  by  the  larva  of  the  May-beetle,  are  hatched 
in  the  digestive  canal,  and  the  embryos,  by  burrowing  through  the  in- 
testinal wall,  find  their  way  into  the  bod3'-cavity  where  they  become 
encysted.  In  this  state  they  may  continue  to  live  through  the  larval 
and  pupal  stages  and  even  after  the  maturity  of  the  insect.  If  the  hog 
eats  the  May-beetle  in  any  of  these  stages  containing  the  cyst,  the  cyst 
Avail  is  digested  away  and  the  freed  larval  worm  attaches  by  its  cephalic 
hooks  to  the  intestinal  mucosa  whei'c  it  attains  full  development. 

Occurrence,  Pathogenesis  and  Symptoms. — The  giant  intestinal 
worm  of  the  hog  is  quite  common  in  the  United  States,  especially  so  in 


THE  THORN-HEADED  WORM.    THE  LEECHES       307 


the  southern  portion.  The  miplantation  of  the  worms  upon  the  in- 
testinal wall  b}'  means  of  their  hooked  rostrum  causes  limited  infiam- 
mator}'  areas  of  red  or  3'ellowish  color.  The 
tumifaction  of  the  wall  causes  the  serosa  to 
be  pushed  out  in  the  form  of  nodules  which 
may  be  of  yellowish  color  and  somewhat 
tubercular  in  appearance.  Exceptionally  it 
has  been  observed  that  the  parasite  has  bored 
through  the  walls  of  the  intestine  and  given 
rise  to  a  purulent  peritonitis. 

As  applies  to  helminthiasis  in  general,  the 
disturbances  which  these  worms  produce  will 
be  in  proportion  to  their  number.  Pain  may 
be  evidenced  b}'  continual  grunting  and  rest- 
lessness, and  there  is  the  general  derangement 
of  digestion  and  the  unthrift  usual  to  hea\y 
invasion  of  the  intestines  by  worms.  Young 
pigs  suffer  most  and,  in  these  particularh', 
there  may  be  nmscular  twitchings  and  epilep- 
tiform seizures,  such  s\nuptoms  usually  l^eing 
followed  by  death. 

Treatment. — Due  to  the 
firm  attachment  of  the 
worms,  little  or  nothing  can 
be  accomplished  by  treat- 
ment.    If  this  is  attempted, 

the  same  remedies  may  be  used  as  recommended  for  the 
ascarids  (p.  241). 


Fig.  165. — Gigantorhynchus 
hirudinaceus,  —  natural  size 
(drawn  from  specimen). 


Class  II.    Annelida 


Fig.  166.  — 
Armed  cephalic 
extremity  of  Gi- 
gantorhynchus hi- 
rudinaceus, —  en- 
larged. 


Coelhelminthes  (p.  216). — The  annulated  worms  differ 
from  those  of  the  class  Nemathelminthes  in  having  a 
segmented  body  cavity  with  corresponding  ringing  or 
annulation  of  the  body  wall.  The  earthworm  is  usually 
taken  for  type  study  of  the  group. 
Order  Hirudinea.  Annelida  (p.  307). — This  order  includes  the 
leeches  which  differ  in  many  respects  from  typical  annelids.  The  body 
is  flattened  doiso-ventrally  and  lacks  the  appendages  for  locomotion 
(setae)  characteristic  of  other  forms.  Locomotion  is  accomplished  by 
two  suckers,  one  at  the  posterior  end,  used  only  for  locomotion  and 
attachment,  the  othei-  surrounding  the  mouth,  used  for  locomotion 
and  attachment  and  also  for  sucking  the  food.  In  moving  from  place 
to  place  the  head  end  is  thrust  forward  and  attached  by  the  sucker. 
The  hind  sucker  is  then  released  and  brought  close  to  the  anterior  sucker 


308 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


by  a  looping  up  of  the  bod}-,  the  anterior  sucker  being  again  advanced 
and  the  process  repeated.  They  can  also  swim  freely  by  snake-like 
movements  in  the  water.  The  body  surface  i?  transverseh'  striated, 
gi^dng  the  appearance  of  a  large  number  of  segments.  The  striations, 
however,  are  in  excess  of  the  true  segmentation  representing  the  somites, 
the  primitive  segment  rings  being  divided  bj^  secondary-  striations. 
The  alimentary  canal  has  a  nmnber  of  paired  sac-like  protuberances 
var3'ing  in  number  according  to  species.  When  the  leech  gorges  itself 
these  sacular  pockets  are  filled  with  blood  upon  which  the  animal  maj^ 
live  for  some  time  before  again  feeding.  The  bod}-  cavity  is  reduced  by 
the  connective  tissue  and  musculature  to  a  number  of  tubular  sinuses. 

The  leeches  are  hermaphroditic  and  copulate  reciprocal^  (cross 
fertihzation).  As  in  the  earthworms,  certain  of  the  somites  at  the  time 
of  reproduction  develop  into  a  clitellum  which  secretes  porous  cocoons 
in  which  the  eggs  are  deposited. 

The  leeches  to  be  considered  come  under  one  family,  the  Gnathobdel- 
lidse,  which  have  the  pharynx  provided  with  three  semicircular  chitinous 
plates  or  jaws,  each  armed  on  its  free  edge 
with  numerous  teeth.  The  Rhynchobdellidse 
are  without  jaws.  This  family  contains  species 
which  attack  fishes  and  invertebrates  and  occa- 
sionally water  fowl. 

1.  Haemopis  sanguisuga.  The  horse  leech. 
(Fig.  167).  Hirudinea  (p.  307).— Dorsally  this 
leech  is  greenish  brown  or  sometimes  reddish 
in  color;  ventrally  dark  gray,  reddish  gray,  or 
black.  Generally  the  body  has  four  to  six  longi- 
tudinal rows  of  closely  set  dark  points  which 
may  be  somewhat  indistinct.  The  body  is 
widest  in  the  middle,  gradually  narrowing  an- 
teriorly, and  is  composed  of  ninety-five  to 
ninety-seven  segments.  It  is  rounded  dorsally, 
flattened  ventrallj^,  soft,  viscid,  and  capable  of 
great  extension  and  retraction.  The  oral  sucker 
is  slightly  concave,  having  at  its  center  the 
mouth  which  is  in  the  form  of  a  three-rayed 
star  (Fig.  167).  Each  of  these  ray-like  sHts 
permits  the  passage  of  a  jaw,  the  teeth  of  which  wound  the  mucous 
membrane  and  thus  enable  the  leech  to  suck  blood  while  it  holds  on 
by  means  of  the  oral  sucker.  There  are  ten  indistinct  eyes  located 
anteriorly  on  the  dorsal  surface.  The  \"ulva  is  a  transverse  slit  located 
five  rings  behind  the  male  orifice,  or  between  the  twenty-ninth  and 
thirtieth  rings. 

In  fecundation  two  individuals  come  together  l^v  their  ventral  sur- 


FiG.  167. — Haemopis  san- 
guisuga. Oral  sucker  of 
same  at  right. 


THE  THORN-HEADED  WORM.    THE  LEECHES        309 

faces  in  opposite  directions,  each  having  the  part  of  male  and  female. 
After  the  cross  fertilization  is  accomplished  there  forms  around  the  part 
of  the  body  where  the  sexual  organs  are  located  a  clitellmn  Avhich  is  a 
sort  of  girdle  secreting  the  capsules  with  which  the  eggs  become  sur- 
rounded. The  leeches  then  bury  themselves  in  damp  ground  where  the 
eggs  are  deposited  and  incubation  proceeds,  this  process  occupying 
about  twenty-eight  days. 

2.  Hirudo  medicinaiis.  The  medicinal  leech.  Hirudinea  (p.  307).— 
This  species  is  a  little  smaller  than  the  horse  leech.  The  dorsal  surface 
is  darker  than  the  ventral  and  is  usually  marked  with  six  longitudinal 
reddish  stripes.  The  ventral  surface  is  usually  olive  green  and  may 
be  more  or  less  spotted. 

This  leech  was  once  extensively  employed  in  medical  practice  for  the 
abstraction  of  blood. 

All  of  the  domesticated  animals  and  man  are  attacked  by  Haemopis, 
probably  the  horse  most  frequently.  The  leeches  live  in  ponds  and 
springs  where  the  animals  are  likety  to  drink  and  are  conveyed  to  the 
mouth  with  the  water.  Those  taken  up  are  usually  the  young  ones, 
these  keeping  near  the  surface  of  the  water,  while  the  adults  usually 
lie  in  the  mud  at  the  bottom.  Having  thus  gained  access  to  the  nmcous 
membranes,  they  fix  upon  the  lips,  cheeks,  pharjmx,  or  other  parts  of 
the  mouth.  They  may  enter  the  nasal  cavities  through  the  nostrils 
direct,  or  they  may  attach  to  the  eyelids.  While  holding  fast  in  these 
positions  by  their  oral  and  caudal  suckers,  the  leeches  lacerate  the 
mucous  membrane  with  their  cutting  jaws  and  become  gorged  with 
blood.  They  then  detach  and  pass  from  their  host,  or  they  may  attach 
to  another  part  of  the  mucous  membrane  and  renew  their  feeding. 

The  effect  of  the  infestation  will  depend  upon  the  number  of  leeches 
present,  and  this  is  extremely  variable.  It  is  estimated  that  a  single 
leech  when  engorged  will  hold  about  eight  cubic  centimeters  (two  drams) 
of  blood.  The  host  suffers  an  additional  loss  from  the  fact  that  there  is 
considerable  hemorrhage  from  the  wounds  after  the  engorged  leeches 
have  become  detached.  Heavy  invasions,  therefore,  are  capable  of 
bringing  about  considerable  depletion  with  evidences  of  anaemia,  as 
paleness  of  visible  mucous  membranes,  edemas,  and  emaciation.  A 
fatal  asphyxia  may  develop  from  edema  of  the  pharynx  which  may  be 
contributed  to  by  the  mechanical  obstruction  offered  by  the  leeches  in 
this  location. 

Treatment. — AVhere  exploration  of  the  mouth  or  nasal  passages 
reveals  the  presence  of  leeches,  those  which  are  accessible  may  be  re- 
moved by  forceps  or  with  the  hand  wrapped  in  a  towel.  Vinegar,  or  a 
strong  solution  of  common  salt  repeatedly  applied  with  a  view  to  causing 
them  to  release  their  hold,  is  recommended  by  some,  but  the  effective- 
ness of  such  treatment  can  only  apply  to  the  leeches  with  which  the  liquid 


310  PARASITES  OF  THE  DOMESTIC  ANIMALS 

comes  in  contact,  many  of  which  maj'^  be  so  far  back  in  the  passages  as 
not  to  be  reached. 

A  method  which  is  probably  better  than  the  syringe  in  the  appHca- 
tion  of  this  treatment  consists  in  firmly  attaching  a  small  sponge  to 
the  end  of  a  probe,  such  as  a  piece  of  rigid  rubber  tubing.  The  sponge 
is  saturated  with  salt  solution  and,  preferably  with  the  use  of  a  mouth 
speculum,  passed  back  over  the  soft  palate  and  pharynx.  In  the  same 
manner  it  may  be  apphed  deeply  into  the  nasal  passages,  the  tube  being 
inserted  slowly  and  with  a  rotary  movement. 


n 


PART  III 
THE  PATHOGENIC  PROTOZOA 

CHAPTER  XXVI 

PHYLUM  IV.    PROTOZOA 

This  division  includes  the  most  primitive  organisms  belonging  to  the 
animal  kingdom.  While  some  can  be  detected  b.y  sharp  eyes  as  tiny 
swinmiing  specks,  most  all  are  so  small  that  they  can  only  be  seen  with 
the  aid  of  the  microscope.  The  individual  animal  is  constituted  by  a 
single  cell,  which,  with  a  difference  in  development,  characteristicall}^ 
distinguishes  the  Protozoa  from  other  animal  groups.  In  most  cases 
they  live  independently  of  each  other,  but  not  rarely  a  number  are 
associated  in  colonies.  Each  individual  in  such  a  colony  is,  as  a  rule, 
physiologically  complete,  that  is,  performing  within  itself  all  of  the 
functions  necessary  to  its  life  and  reproduction.  The  colonization, 
however,  tends  to  a  degree  of  differentiation  and  interdependence,  and 
in  certain  cases  there  are  morphological  and  physiological  differences 
among  the  individuals  so  grouped,  these  usually  being  related  primarily 
to  the  functions  of  nutrition  and  reproduction. 

The  protozoan  colony  may  be  said  to  differ  from  the  metazoan  in  that 
each  cell  of  the  colony  represents  an  animal  which  may  live  unassociated 
with  other  cells,  while  in  the  metazoan  the  individual  is  comprised  l\v 
the  aggregation  of  cells  among  which  there  is  a  morphological  differentia- 
tion corresponding  to  special  functions  which  are  distributed  among 
adaptively  specialized  cell-groups;  the  bod\'-cells  are  not  capable  of  free 
existence  and  they  can  only  live  as  integral  parts  of  the  metazoan. 
The  Protozoa  being  single-celled  animals,  there  is  a  further  fundamental 
difference  in  their  development,  since  it  essentially  follows  that  there  is 
no  formation  of  germ  layers  as  occurs  in  all  Metazoa.  The  division  or 
budding  of  the  protozoan  cell  results  directlj'  in  a  new  generation  and 
not  in  the  development  of  germinal  tissue  layers,  though  the  new  cells 
may  remain  aggregated  to  form  a  colony. 

While  the  Protozoa  are  referred  to  as  the  most  simple  rejiresentatives 
of  the  animal  kingdom,  they  present,  nevertheless,  considerable  differ- 
ences in  form  and  modification  of  the  cytoplasm,  the  functions  of  mo- 
tion, alimentation,  excretion,  and  reproduction  being  performed  by  a 


312  PARASITES  OF  THE  DOMESTIC  ANIMALS 

much  greater  specialization  in  some  than  in  others.  While  a  nucleus  is 
not  easily  demonstrable  in  certain  of  the  Protozoa,  most  have  one  or 
more  distinct  nuclei,  in  this,  as  in  other  respects,  possessing  the  essential 
parts  of  a  typical  cell. 

Ameba. — A  simple  representative  of  the  Protozoa  is  the  Ameba 
(Fig.  168)  which  may  be  found  in  .most  any  still  water,  most  readily  in 
the  ooze  ujion  the  bottom  or  adhering  to  leaves  or  other  submerged 


Fig.  168. — -Ameba  proteus  (after  Crawley,  from  Doflein;  Cir. 
No.  194,  Bureau  An.  Ind.,  U.  S.  Dept.  Agr.). 

objects.  Search  of  such  material  under  the  low  power  of  the  microscope 
will  reveal  this  organism  as  a  minute  protoplasmic  particle  which  slowly 
changes  its  shape  and  location  by  a  peculiar  flowing  and  extension  of 
the  cytoplasm  at  one  or  more  points,  forming  irregular,  often  finger-like, 
projections, — the  pseudopodia.  These  may  be  withdrawn  or  the  whole 
substance  of  the  animal  may  appear  to  flow  into  one  of  the  projections; 
by  this  manner  of  locomotion  it  may  slowly  pass  out  of  the  microscopic 
field.  Close  study  of  the  organism  will  reveal  two  distinct  regions,  an 
outer  hyaline, — the  ectoplasm  (ectosarc),  and  a  central  more  granular 
and  less  transparent  part, — the  endoplasm  (endosarc) .  Within  the  latter 
may  be  seen  the  food  vacuoles  which  are  rounded  or  oval,  of  varying 


PROTOZOA  313 

size,  and  inclose  granules  of  food  material.  At  intervals  clear  globules 
may  be  seen  to  gradually  form  within  the  cytoplasm  and  then  suddenly 
contract  and  disappear.  These  are  the  contractile  vacuoles  which  on 
contracting  empty  their  fluid  contents  to  the  exterior.  They  are  rudi- 
mentary cell  organs  for  the  elimination  of  injurious  substances  and  differ 
from  the  food  vacuoles  in  having  a  definite  place  in  the  cell  as  well  as  in 
their  approximately  constant  number.  Young  amebae  usually  have 
within  the  endoplasm  a  single  nucleus  but  they  may  early  become 
multinucleate.  All  of  the  vital  functions  appear  to  be  under  the  con- 
trol of  the  nucleus;  experimental  removal  of  the  nuclei  has  shown  that 
Protozoa  thus  treated  cannot  properly  perform  their  functions  and  soon 
perish. 

In  feeding  the  ameba  merel}^  flows  around  the  ol)jcct  which  it  is  to 
use  as  food;  becoming  thus  inclosed  in  the  cj'toplasni  the  nutritive 
elements  are  digested  and  assimilated.  Circulation  is  limited  to  the 
streaming  movements  of  the  cj'toplasm,  and  respiration  is  carried  on  by 
absorption  of  oxygen  from  the  surrounding  water. 

Reproduction  in  ameba  is  by  fission  or  budding.  Before  division  of 
the  cell  changes  occur  in  the  nucleus  involving  a  separation  of  the 
nuclear  parts  with  the  formation  of  two  distinct  nuclei.  These  separate 
and  during  the  process  the  cell  constricts,  finally  dividing  completely 
with  each  part  inclosing  one  of  the  new  nuclei.  In  some  cases  the  cell 
becomes  spherical  and  secretes  a  protecting  mem])rane  around  itself 
before  division;  the  outer  membrane  becomes  hard  and  adapted  to  re- 
sist drying  and  extremes  of  temperature,  the  organism  assuming  in  this 
condition  a  resting  or  encysted  stage.  Encysted  individuals  usually 
divide  into  more  than  two;  there  may  be  four,  eight,  or  even  hundreds 
of  small  amebae  resulting  from  the  reproductive  process.  In  multi- 
nucleate forms  it  frequenth'  happens  that  the  division  is  into  as  many 
parts  as  there  are  nuclei. 

Parasitism  of  the  Protozoa 

In  1881  Laveran,  a  phj'sician  in  the  French  army,  distinctively 
directed  attention  to  the  Protozoa  as  a  cause  of  disease  in  animals  by 
his  discovery  that  the  cause  of  malaria  in  man  is  a  protozoan  which, 
entering  the  red  blood  cells,  destro^vs  them  and  in  this  way  causes  the 
anaemia  characteristic  of  the  disease.  Later  it  was  demonstrated  that 
this  malarial  organism  is  transmitted  b}^  a  mosquito  and  that  this  is  the 
only  way  that  the  disease  can  be  acquired.  This  discovery  served  to 
indicate  lines  of  research  looking  to  insects  and  other  arthropods  as 
essential  carriers  of  other  forms  of  pathogenic  Protozoa,  in  which  field 
much  has  already  been  accomplished. 

Theobald  Smith,  in  1892,  found  that  Texas  fever  of  cattle  is  caused 


314  PARASITES  OF  THE  DOMESTIC  ANIMALS 

by  a  protozoan  which,  though  not  identical  with  it,  is  allied  to  the 
malarial  parasite,  and,  like  it,  enters  and  destroys  the  red  blood  cells. 
In  this  case  the  infecting  organism  has  been  found  to  be  conveyed  from 
animal  to  animal  by  a  certain  species  of  tick  {Margaropus  annulatus, 
p.  144),  and  it  is  now  known  that  the  presence  of  the  tick  is  essential  to 
such  transmission. 

Trypanosomes  were  first  studied  in  mammahan  blood  by  Lewis  in 
1877,  who  observed  them  in  the  blood  of  a  rat.  Three  years  later 
Trypanosoma  evansi  was  studied  as  the  cause  of  surra,  a  disease  of  horses 
of  Asiatic  countries,  the  transmitting  agent  of  which  is  thought  to  be  a 
blood  sucking  fly  (Tabanus,  p.  332). 

Bruce,  in  1894,  demonstrated  that  a  trypanosome  {Trypanosoma 
hrucei)  was  the  specific  organism  causing  the  fatal  nagana  or  tsetse 
fly  disease  of  horses  and  other  domestic  animals  of  Africa.  He  showed 
conclusively  that  blood-sucking  invertebrates,  mainly  the  tsetse  flies 
(Glossina,  p.  44),  are  responsible  for  its  transmission  from  the  blood  of 
wild  immune  to  the  blood  of  susceptible  domesticated  animals. 

The  relationship  of  the  tsetse  fly  to  human  trypanosomiasis  was  shown 
in  much  the  same  way  as  that  followed  in  the  researches  of  Bruce. 
African  sleeping  sickness  of  man  was  originally  confined  to  the  West 
Coast;  it  has  spread  eastward  and  is  now  a  serious  menace  to  the  develop- 
ment of  Central  Africa.  In  1902  the  infecting  organism  of  this  fatal 
disease  was  discovered  to  be  a  trypanosome  {Trypanosoma  gambiense) 
carried  from  host  to  host  mainly  by  a  tsetse  fly.  Students  of  protozool- 
ogy have  since  shown  that  mosquitoes,  lice,  and  leeches  may  carry 
trypanosomes,  and  that  piercing  flies,  therefore,  may  not  alone  be 
responsible  for  the  spread  of  the  diseases  which  are  caused  by  these 
Protozoa. 

The  instances  above  cited  will  serve  to  direct  attention  to  the  im- 
portance of  the  Protozoa  from  the  viewpoint  of  their  pathogenicity  both 
in  its  economic  relation  and  as  regards  disease  in  man.  Up  to  the  present 
time  the  Protozoa  as  disease-producing  organisms  have  not  received 
the  attention  in  the  United  States  that  has  been  given  them  by  inves- 
tigators in  Africa  and  Europe.  This  is  probably  due  to  the  fact  that, 
though  this  country  is  not  free  from  pathogenic  trypanosomes,  it  has 
thus  far  escaped  the  ravages  of  the  trypanosomiases  of  Africa,  Asia, 
and  South  America,  to  which  countries  sleeping  sickness,  kala-azar 
(leishmaniasis),  nagana,  surra,  and  mal  de  caderas  have  to  the  present 
time  confined  their  plague.  A  sHght  acquaintance  with  the  subject, 
however,  is  sufficient  to  dispel  a  feeling  of  security  based  upon  the 
erroneous  impression  that  these  diseases  are  restricted  to  tropical 
countries  or  that  their  spread  depends  upon  the  presence  of  a  certain 
kind  of  fly.  It  has  already  been  noted  that  the  African  trypanosomiases 
may  not  depend  wholly  upon  the  tsetse  flies  for  their  existence  and 


PROTOZOA  315 

spread;  surra  and  mal  de  caderas  certainly  do  not,  as  these  are  diseases 
of  Asia  and  South  America  respectively,  and  tsetse  flies  are  not  found  in 
either  of  these  countries.  There  is,  in  fact,  no  reason  to  doubt  that  any 
blood-sucking  fly  can  transmit  trypanosomes  from  the  blood  of  one 
host  to  that  of  another.  In  view  of  this  the  horse  and  stable  flies,  so 
common  in  North  America,  would,  in  the  presence  of  trypanosomiasis, 
amply  supply  the  means  for  its  sprej^d. 

In  recent  years  important  advances  have  been  made  in  the  study 
of  the  role  of  arthropods  in  the  spread  of  disease.  Common  knowledge 
as  to  its  powers  for  carrying  bacterial  infection  has  condemned  the 
fly  to  the  swat,  but  it  is  as  essential  hosts,  and  not  as  purely  mechanical 
carriers,  that  these  invertebrates  furnish  the  greatest  field  for  research. 
Much  has  already  been  accomphshed  in  working  out  the  life  histories 
of  the  parasites  of  insects  and  ticks,  including  parasites  which  have  no 
api^arent  connection  with  diseases  of  higher  animals,  for  these,  po- 
tentialh'  at  least,  may  not  be  so  harmless  to  higher  animals  as  may  at 
first  appear.  Change  of  habitat,  as  from  one  part  of  the  body  to  another 
in  the  same  host,  or  from  a  host  of  one  species  to  that  of  another,  fre- 
quently leads  to  great  alteration  in  the  mode  of  life  of  an  organism 
which,  relatively  harmless  in  the  insect,  may  in  the  vertebrate  evolute 
into  more  harmful  parasitism  with  the  development  of  pathogenicity'. 
The  newer  a  parasite  is  to  the  animal  harboring  it,  the  less  it  is  in  har- 
mony with  its  environment.  Protozoa  which  produce  acute  forms  of 
disease  have  less  adaptation  to  their  environment  than  those  producing 
a  chronic  type  of  malady.  This  discord  between  parasite  and  host  is 
manifested  by  acute  disturbances  which  maj'  result  in  the  death  of  the 
infected  animal.  Such  parasitic  diseases  of  a  chronic  course  are  usually 
correlated  with  a  greater  degree  of  adaptation  of  the  parasite  to  its 
host  and  also  with  acquired  resisting  powers  of  the  host  to  the  specific 
action  of  the  parasite. 

The  scale  of  evolution  through  the  saprophytic,  parasitic,  and  patho- 
genic is  thus  exhibited  by  certain  groups.  The  Spirochetida,  long, 
delicate  Protozoa  with  a  corkscrew-formed  body,  may  be  found  as  in- 
habitants of  the  body-cavities,  of  normal  mucous  surfaces,  of  inflamed 
mucous  surfaces,  as  parasites  which  have  penetrated  the  tissue,  and  as 
blood  parasites.  This  series  is  sufficient  to  show  how  parasitism  may 
evolute  by  various  gradations  from  harmless  commensalism  to  distinct 
parasitism  and  pathogenicity,  ^^^len  the  habit  of  living  in  inflamed  or 
ulcerated  tissues  is  reached  the  power  of  penetrating  healthy  tissues 
soon  follows  which,  with  the  multiplication  of  the  spirochetes  in  such 
situations,  causes  destruction  of  invaded  tissue  and  local  disturbances. 
The  products  of  this  tissue  destruction,  together  with  those  coming  from 
the  dead  bodies  of  the  parasites,  form  toxins  which,  getting  into  the 
blood,   produce  the  general  toxemic  symptoms.     The  final  stage  of 


316  PARASITES  OF  THE  DOMESTIC  ANIMALS 

malignant  parasitism  is  reached  when  the  spirochetes  acquire  the  habit 
of  Uving  in  the  blood.  In  this  case  it  is  evident  that,  except  under  cer- 
tain conditions  of  contact,  the  transfer  from  host  to  host  cannot  be  direct, 
but  that  the  intervention  of  an  intermediate  host  is  necessary.  This  must 
be  a  blood-sucking  invertebrate,  and,  in  certain  known  cases  of  spiroche- 
tosis of  domestic  animals,  has  been  found  to  be  a  tick,  as  the  tick  Argas 
miniatus,  the  carrier  of  Spirocheta  galUnarum  which  causes  a  spiroche- 
tosis in  fowls,  and  the  cattle  tick  Boophilus  decolomtiis,  the  inter- 
mediate host  of  Spirocheta  theileri,  the  cause  of  a  disease  among  South 
American  cattle. 

The  malaria  parasites  afford  stud}-  in  the  evolution  of  pathogenicity 
of  other  Protozoa.  These  organisms  indicate  in  their  morphology'  and 
development  that  they  are  closely  allied  to  the  Coccidia,  which  are 
protozoan  cell  parasites  attacking  and  entering  tissue  cells,  especially 
epithelimii,  of  arthropods  and  vertebrates.  There  is  little  doubt  that 
the  malaria  parasites  were  originall}'  Coccidia  of  insects  that,  with 
change  of  hal3itat,  developed  increased  pathogenicity  toward  the  new 
host. 

Granting  this,  we  have,  then,  in  the  malaria  parasites  an  example 
of  the  evolution  of  disease  m  the  past,  while  disease  in  the  making  is 
evidenced  to-day  more  especiall}'  in  the  case  of  certain  parasitic  flag- 
ellates of  the  genus  Herpetomonas. 

The  introduction  of  herpetomads  into  vertebrates  by  the  latter 
swallowing  infected  insects,  or  b}'  the  wa}'  of  wounds  of  the  skin,  has 
been  shown  to  result  in  pathogenic  effects  in  the  vertebrate  host.  A 
series  of  experiments  extending  over  some  six  years  (Fantham  and 
Porter,  Journal  of  Parasitology,  June,  1916)  have  shown  that  certain 
herpetomads  normally  parasitic  in  insects,  when  introduced  into  ver- 
tebrates will  produce  a  condition  resembling  kala-azar,  an  infectious 
disease  of  man  common  in  certain  regions  of  India,  China,  and  countries 
bordering  on  the  Mediterranean,  caused  by  the  herpetomad  Leishmania 
(Herpetomonas)  donovani.  The  sjinptoms  developed  and  the  mor- 
phology of  the  parasite  found  in  the  vertebrate  host  show  that  here  at 
least  are  examples  of  kala-azar  in  process  of  evolution. 

Plate  III. — Evolution-  of  the  Parasite  of  Kala-Azar.  Figs.  1  to  5.  Parasites  of 
kala-azar.  1.  Isolated  parasites  of  different  forms  in  the  spleen  and  liver.  2.  Di%asion 
forms  from  liver  and  bone  marrow.  3.  Mononuclear  spleen  cells  containing  the  parasites. 
4.  Groups  of  parasites.  5.  Phagocjiiosis  of  a  parasite  by  a  polynuclear  leucocyte.  Figs. 
(3  to  15.  Parasites  from  cultures.  6.  First  changes  in  the  parasites.  The  protoplasm  has 
increased  in  bulk  and  the  nucleus  has  become  larger.  7.  Further  increase  in  size.  Vacuoli- 
zation of  the  protoplasm.  S.  Di%-ision  of  the  enlarged  parasite.  9.  Evolution  of  the 
flagella.  10.  Small  piriform  parasite  showing  flagellum.  11.  Further  development  and 
division  of  the  parasite.  12.  Flagellated  trj-panosome-like  form.  13,  14.  Flagellated 
forms  dividing  by  a  splitting-off  of  a  portion  of  the  protoplasm.  15.  Narrow  flagellated 
parasites  which  have  arisen  by  the  type  of  division  shown  in  Figs.  13  and  14.  (After  Craw- 
ley, from  Mense's  "Handbuch,"  after  Leishman,  Cir.  Xo.  194.  Bu.  An.  Ind.,  U.  S.  Dept. 
Agr.). 


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318  PARASITES  OF  THE  DOMESTIC  ANIMALS 

A  brief  review  of  these  conclusions,  drawn  from  the  results  of  ex- 
perimental research,  will  be  sufficient  to  direct  attention,  not  only  to 
the  powers  which  insects  have  as  carriers  of  disease,  but  to  their  poten- 
tial powers  in  the  making  of  disease  as  well. 

Methods  of  Reproduction. — Sexual  and  asexual  methods  of  repro- 
duction alternate  in  free  forms  of  Protozoa,  but  the  asexual  method  is 
usually  limited  to  simple  division  or  budding.  Parasitic  forms,  on  the 
other  hand,  have  acquired  a  more  prolific  means  of  multiplication,  the 
simple  division  and  budding  being  replaced  by  asexual  spore  formation 
as  exemplified  among  the  Sporozoa.  In  the  parasitic  Protozoa,  there- 
fore, two  kinds  of  spores  may  be  present,  the  one  occurring  asexually 
during  the  vegetative  life  in  the  host  and  giving  rise  to  auto-infection 
in  the  same  host,  the  other  sexual,  occurring  at  the  end  of  the  vegetative 
life  of  the  parasite,  preparing  its  germs  to  withstand  the  unfavoral^le 
conditions  of  an  external  environment,  and  giving  rise  to  infection  of 
new  hosts. 

The  asexual  method  of  multiplication,  taking  place  during  the  veg- 
etative life  in  the  host,  is  termed  schizogony  or  schizogenesis,  while  the 
term  sporogony  or  sporogenesis  has  been  given  to  reproduction  by  the 
sexual  method.  The  first  is  sometimes  referred  to  as  the  multiplicative, 
the  second  as  the  propagative  cycle. 

Life  History  of  the  Malaria  Organisms. — AVith  a  view  to  an  ele- 
mental conception  of  these  reproductive  and  infective  processes  in  the 
Sporozoa,  the  life  history  of  the  organisms  producing  malaria  in  man 
affords  a  clear  example  for  stud3^ 

Malaria  was  the  first  of  the  human  diseases  in  which  it  was  proved 
that  a  protozoan  is  the  direct  cause,  and  by  1901  the  disease  was  as 
thoroughly  understood  as  perhaps  any  other  due  to  a  germ.  The  malaria 
parasites  belong  with  the  genus  Plasmodium,  so  named  from  their  early 
supposed  resemblance  to  some  of  the  plasmodia-forming  fungi.  They 
are  usually  considered  under  three  forms  with  which  three  well-marked 
types  of  malaria  are  associated.  These  may  be  briefly  summarized  as 
follows : 

1.  Plasmodium  vivax. — Cause  of  tertian  fever;  paroxysms  occur  every 
forty-eight  hours;  incubation  period  about  two  weeks.  Temperate  cli- 
mates, also  in  tropics  and  subtropics. 

2.  Plasmodium  falciparum  (P.  prcecox). — Cause  of  estivo-autumnal 
fever;  paroxysms  every  twenty-four  hours;  incubation  period  usually 
from  ten  to  twelve  days.    Tropics  and  subtropics. 

3.  Plasmodium  malarice. — Cause  of  quartan  fever;  paroxysms  every 
seventy-two  hours;  incubation  period  about  three  weeks.  Tropics  and 
subtropics. 

Two  distinct  cycles  are  involved  in  the  life  history  of  the  malaria 
organisms.    The  first  takes  place  in  the  blood  of  the  human  patient  and 


PROTOZOA  319 

is  known  as  the  asexual  or  schizogonic  cycle,  during  which  the  plasmodia 
niultipty  by  the  asexual  method  or  schizogony.  The  second  occurs  in 
the  body  of  a  mosquito  and  is  the  sexual  or  sporogonic  cycle,  involving 
reproduction  b}'  the  sexual  method  or  sporogony.  A  third  phase  is  to 
be  recognized  during  which  the  female  gametocj'tes  sporulate  without 
fertilization.  This  is  referred  to  as  the  parthenogenetic  cycle.  It  is' 
passed  within  the  body  of  the  human  host  and  explains  the  recurrence 
of  malaria  after  more  or  less  prolonged  periods  of  latency. 

The  Schizogonic  or  Asexual  Cycle. — The  asexual  cycle  begins  with 
the  infection  of  the  human  })lood  with  the  sporozoites  by  the  bite  of  a 
mosquito  of  the  genus  Anopheles  (p.  26).  The  sporozoite  is  spindle- 
shaped  and  on  entering  the  blood  at  once  penetrates  a  red  corpuscle 
where  it  takes  a  ring-like  form,  referred  to  as  the  signet  ring  stage,  Liv- 
ing at  the  expense  of  the  corpuscle,  the  organism  grows  rapidly  until  it 
more  or  less  fills  the  corpuscle.  At  this  stage  it  is  known  as  the  schizont, 
which  is  the  period  of  its  ameboid  movement  and  highest  vegetative  ac- 
tivity. As  the  schizont  matures  its  nucleus  breaks  up  into  a  number  of 
daughter  nuclei,  each  becoming  surrounded  by  a  spherical  portion  of 
protoplasm  to  form  a  small  reproductive  element. — the  merozoite,  or 
asexually  formed  spore.  Finally  the  corpuscle  is  broken  down  and  the 
swarm  of  merozoites  is  liberated  in  the  ])lood-plasma.  Coming  from  the 
same  original  brood,  the  parasites  all  sporulate  and  become  liberated  in 
the  blood  at  the  same  time;  this  results  in  the  constantly  increasing 
number  of  merozoites  l)eing  li))erated  at  stated  intervals  with  corre- 
sponding intervals  of  paroxysm  in  the  host.  The  general  toxic  effect 
upon  the  malaria  patient  is  contributed  to  by  the  accumulated  waste 
products  of  the  parasite's  metabolism  which  pass  into  the  plasma  with 
the  liberation  of  the  merozoites.  Each  liberated  merozoite  now  enters 
another  corpuscle,  and  the  asexual  cycle  is  repeated  in  from  twenty- 
four  to  seventy-two  hours  according  to  the  species  of  the  infecting  or- 
ganism. 

This  process  of  multiplication  may  continue  for  an  indefinite  tune 
or,  by  analogy  with  other  parasitic  Protozoa,  until  the  vitality  is  ex- 
hausted. Asexual  merozoites  are  greatly  in  the  majority,  but  certain  of 
them  are  potentially  sexual  and  i-equire  a  longer  time  to  fully  develop 
into  males  and  females  when  they  are  known  as  male  and  female  game- 
tocytes.  Up  to  this  time  they  are  still  intracorpuscular  and,  in  the 
estivo-autumnal  or  pernicious  type  of  fever,  appear  as  large  crescents. 
The  female  crescent  (macrogametocyte)  has  numerous  pigment  gran- 
ules collected  in  the  center;  the  male  (microgametocyte)  is  the  mother 
cell  of  the  male  reproductive  elements  (microgametcs).  The  nucleus 
of  the  male  cell  divides  into  a  number  of  daughter  nuclei  which  migrate 
to  the  periphery  and  become  the  nuclei  of  the  flagelliform  microgametes. 
These  bodies  are  constantlv  in  the  l)lood  after  the  first  few  paroxysms. 


320  PARASITES  OF  THE  DOMESTIC  ANIMALS 

If  the  blood  is  now  di-awn  by  an  anopheline  mosquito  further  changes 
take  place-. 

The  Sporogonic  or  Sexual  Cycle. — In  the  intestine  of  the  mosquito 
the  female  gametocyte  undergoes  certain  nuclear  changes  preparatory 
to  fertilization;  the  cell  becomes  rounded  or  oval  in  form,  and  is  now 
known  as  the  macrogamete.  From  the  male  gametocyte  there  are  ex- 
truded from  three  to  six  fiagelliform  filaments  corresponding  in  number 
to  the  peripheralh'  disposed  daughter  nuclei.  These  filaments  detach 
from  the  mother  cell  to  become  the  actively  motile  microgametes,  which 
are  analogous  to  the  spermatozoa  of  higher  animals.  Thus  the  flag- 
ellated parent  body  maj'  be  referred  to  as  a  microgametoblast;  produc- 
ing the  male  sexual  elements  or  microgametes. 

Fertilization  of  the  macrogamete  is  brought  about  by  its  penetration 
by  one  of  the  microgametes.  The  fertihzed  macrogamete  now  becomes 
the  ookinete  or  zj-gote,  in  which  stage  it  passes  by  a  vermiform  move- 
ment into  and  through  the  epithelium  of  the  mosquitoe's  mid-intestine 
and  comes  to  rest  just  beneath  the  outer  lining  membrane.  Here  it 
rapidly  grows,  the  nucleus  divides,  and  by  the  third  to  the  fifth  day  it  has 
formed  a  cyst  in  which  there  are  many  nuclei,  each  to  become  the  nucleus 
of  a  minute  body, — the  sporoblast.  The  sporoblasts,  by  division,  form  a 
number  of  germs, — the  sporozoites,  spindle-shaped,  nucleated  bodies 
which  are  mature  after  a  period  of  ten  to  fourteen  days  in  the  body  of 
the  mosquito.  On  reaching  maturity,  the  sporozoites  are  liberated  into 
the  body  cavity  of  the  insect  where  they  are  carried  about  b}^  the  body 
fluids,  collecting  eventual^  in  the  salivary  glands.  From  here  they 
pass  to  the  piercing  proboscis  from  which,  with  the  next  bite  of  the  mos- 
quito, many  may  pass  into  the  blood  of  another  human  victim  to  begin 
the  asexual  cvcle. 


Plate  IV.^ — Life  Cycle  of  the  Malaria  Parasite.  1.  Free  sporozoite,  either  in 
salivary  glands  of  the  mosquito  or  in  blood  of  man.  2.  Penetration  of  the  sporozoite  into  a 
red  blood  corpuscle.  3  to  6.  Growth  of  trophozoite.  7,  8.  Division  of  trophozoite  which 
brings  about  destruction  of  the  blood  corpuscle  and  the  release  of  the  merozoites  in  the 
blood  stream.  The  free  merozoites  then  enter  new  blood  corpuscles,  and  this  cycle  may 
be  repeated  many  times.  Finally,  however,  the  sexual  cj'cle  is  initiated  as  follows:  9a  to 
12a.  Growth  and  differentiation  of  female  cell.  9b  to  12b.  Growth  and  differentiation  of 
male  cell.  1.3a,  13b.  The  male  and  female  cells  are  swallowed  by  a  mosquito.  14a.  Matu- 
ration of  female  cell.  14b.  Formation  of  microgametes.  15b.  Free  microgamete.  16. 
Fertilization.  17.  Ookinete.  18,  19,  20.  The  ookinete  attacks  and  penetrates  a  cell  of 
the  intestine  of  the  mosquito,  and  passes  completely  through  the  epithelium,  coming  to 
rest  in  the  peri-intestinal  tissue.  (There  is  not,  in  life,  the  reduction  in  size  indicated  by 
the  figure.)  21  to  25.  Stages  in  the  development  of  the  cyst  and  formation  of  the  sporozo- 
ites. 26.  Migration  of  the  sporozoites.  27.  Sporozoites  in  the  salivary  glands  of  the 
mosquito.  13c  to  17c.  These  figures  portray  the  cycle  which  is  supposed  to  account  for 
cases  where  malaria  is  latent  for  a  longer  or  shorter  period.  Ordinarily,  unless  removed  Ijy 
a  mosquito,  the  differentiated  male  and  female  cells  (12a  and  12b)  die,  but  under  certain 
conditions  the  latter  may  continue  to  live  in  the  blood,  to  give  rise  to  a  renewal  of  the 
disease.  (After  Crawley,  from  Mense's  "Handbuch,"  after  Grassi  and  Schaudinn,  Cir. 
No.  194,  Bu.  An.  Ind.,  U.  S.  Dept.  Agr.). 


3^22  PARASITES  OF  THE  DOINIESTIC  ANIMALS 

In  the  parthenogenetic  phase,  which  occurs  in  the  human  host,  the 
female  gametocyte  sporulates  without  fertiHzation.  After  months  of 
latency  these  spores  may  pass  into  the  blood  current  and  enter  the 
corpuscles,  bringing  about  a  recurrence  of  malaria  after  its  apparent 
cure. 

It  should  be  noted  in  the  sexual  cycle  that  the  formation  of  the  spo- 
roblasts  is  similar  to  the  formation  of  corresponding  reproductive  cen- 
ters of  the  Coccidia,  which  pass  a  portion  of  their  cj^cle  external  to  a  host 
and  which  are  elsewhere  referred  to  (p.  337).  The  sporoblasts  of  the  Plas- 
modia, however,  differ  from  those  of  the  Coccidia  in  having  no  protect- 
ing membrane  or  capusle,  in  the  absence  of  which  protection,  the  spo- 
rozoites  are  unfitted  for  existence  outside  the  body  of  a  host  animal. 

Classification. — Accorchng  to  their  mode  of  life,  Calkins  divides  the 
parasitic  Protozoa  into  the  following  groups.  The  arrangement  is  not 
a  natural  one  and  is  merely  for  descriptive  purposes: 

1.  Enterozoic. — Living  in  the  lumen  of  the  digestive  tract. 

2.  Coelozoic- — Living  in  the  coelomic  cavities  of  the  body. 

3.  Cytozoic. — Living  throughout  the  vegetative  period  as  intracel- 
lular parasites. 

4.  Caryozoic. — Passing  into  the  cell  to  find  lodgment  in  the  cell  nu- 
cleus. 

5.  Hematozoic. — Living  in  the  blood  plasma. 

In  some  cases  the  parasite  may  pass  through  a  number  of  these  modes 
of  life.  Thus  the  plasmodia  of  malaria  are  hematozoic  in  the  blood 
current,  cytozoic  in  the  blood  corpuscles,  enterozoic  in  the  digestive 
tract  of  the  mosquito,  and  coelozoic  w^hen  they  pass  as  sporozoites  into 
the  body  cavit.v  of  this  insect. 

In  the  arrangement  of  the  classification  of  the  Protozoa  which  follows, 
only  those  groups  containing  species  of  parasitic  importance  are  given. 

Classification  of  Paeasites  of  the  Phylum  Protozoa 

Phylum  IV.  Protozoa.    P.  311. 
Class  A.  Phizopoda.    P.  324. 
Order  1.  Lobosa.    P.  324. 
Genus  and  Species: 

Ameba  meleagridis.    Host,  turkey.    P.  325. 
Entameba  histolytica.    Host,  man.    P.  326. 
E.  coli.    Host,  man.    P.  326. 
Class  B.  Flagellata.    P.  326. 
Order  1.  Spirochetida.    P.  327. 
Genus  and  Species: 

Spirocheta  gallinarum.    Host,  fowl.    P.  327. 
Order  2.  Trypanosomatida.    P.  328. 


PROTOZOA  323 

Genus  and  Species: 

Trypanosoma  theileii.    Host,  cattle.    P.  329. 

T.  brucei.    Hosts,  equines,  cattle,  etc.    P.  330. 

T.  evansi.    Hosts,  equines,  camel.    P.  332. 

T.  equinum.    Host,  equines.    P.  332. 

T.  equiperdum.    Host,  equines.    P.  333, 

T.  americanum.    Host,  cattle.    P.  330. 

Trvpanoplasma.    P.  329. 
Class  C.  Sporozoa.    P.  336. 
Order  1.  Coccidia.    P.  337. 
Genus  and  Species: 

Eimeria  stiedse.    Host,  rabbit.    P.  342. 

Diplospora  bigemina.    Host,  dog.    P.  342. 

Coccidium  zurni.    Host,  cattle.    P.  343. 

Eimeria  avium.    Host,  chicken.    P.  345. 
Order  2.  Hemosporidia.    P.  347. 
Genus  and  Species: 

Piroplasma  bigeminum.    Hosts,  cattle,  tick.    P.  347. 

Plasmodium  vivax.    Hosts,  man,  mosquito.    P.  318. 

PI.  falciparum.    Hosts,  man,  mosquito.    P.  318. 

PI.  malaria.    Hosts,  man,  mosquito.    P.  318. 
Order  3.  Sarcosporidia.    P.  350. 
Genus  and  Species: 

Sarcocystis  miescheriana.    Host,  pig.    P.  351. 

S.  tenella.    Host,  sheep.    P.  351. 

S.  blanchardi.    Host,  cattle.    P.  351. 

S.  bertrami.    Host,  equines.    P.  351. 


CHAPTER  XXVII 

THE  PROTOZOAN  SUBGROUPS.     DISEASES  DUE  TO 
PROTOZOA 

Class  I.  Rhizopocla.     Protozoa  (p.  311). 

The  Protozoa  of  this  group  lack  permanent  structures  for  locomotion 
and  nourishment,  these  functions  being  performed  by  the  undifferen- 
tiated protoplasm.  For  this  reason  they  are  considered  to  be  the  lowest 
in  position  of  the  Protozoa.  The  class  name — Rhizopoda — has  ref- 
erence to  the  extension  of  the  cytoplasm  in  root-like  processes  or  feet, — 
the  pseudopodia  or  false  feet.  It  is  in  this  manner  that  the  anmial  flows 
over  and  engulfs  its  food,  the  movements  serving  for  locomotion  as  well. 
This  type  of  locomotion  is  known  as  ameboid,  it  having  been  first 
accurately  studied  in  the  Ameba.  It  differs  from  that  of  higher  Pro- 
tozoa in  that  it  is  not  accomplished  by  constant  cell  organs,  as  ciha  and 
fiagella.  A  pseudopodium  is  formed  when  the  cytoplasm  streams  to  a 
point  of  the  body,  the  process  extending  more  or  less  beyond  the  gen- 
eral body  surface;  the  body  may  then  be  drawn  after  it  or  appear 
to  flow  into  it,  the  protrusion  disappearing  and  new  pseudopodia  being 
formed  at  other  points.  By  repetition  of  this  process  a  slow  change 
in  the  position  of  the  organism  occurs,  and  if  particles  of  nourish- 
ment are  encountered  in  such  wandering  they  are  engulfed  by 
the  cytoplasm  within  which  they  become  surrounded  by  a  certain 
amount  of  liquid,  presumably  of  a  digestive  nature,  to  form  the  food 
vacuole. 

The  form  of  the  pseudopodia  varies,  and  this  serves  as  a  factor  in  the 
separation  of  the  rhizopods  into  different  groups.  In  the  Ameba  (Fig. 
168)  they  are  thick  and  finger-like,  while  in  certain  other  forms  they  are 
of  such  delicacy  as  to  appear  like  fine  threads. 

Reproduction  in  Rhizopoda  may  be  accompanied  with  the  formation 
■of  flagellate  spores,  the  ameboid  method  of  motility  being  exchanged 
for  that  of  the  flagellated  Protozoa.  In  this  stage  the  body  becomes 
oval  and  the  flagellum  develops  at  the  end  containing  the  nucleus, 
where  it  persists  during  the  spore  stage. 

The  parasitic  Rhizopoda  belong  with  the  order  Lobosa  which  is  the 
only  one  considered  here.  The  characteristics  of  this  group  have  been 
sufficiently  referred  to  in  the  description  of  the  type  genus  Ameba 
(p.  312).  There  are  but  few  parasitic  species  known,  and  these  are 
included  in  the  two  genera  Ameba  and  Entameba. 


THE  PROTOZOAN  SUBGROUPS  325 

Lnfectious  Entero-Hepatitis  of  Turkeys 

This  disease — connnonly  known  as  blackhead — has  l^een  attributed 
to  an  organism  found  by  Theobakl  Smith  in  the  necrotic  Hver  of  affected 
turkeys  and  named  by  him  Ameba  meleagridis.  That  this  is  an  ameba, 
however,  has  been  questioned.  Certain  other  investigators  consider 
the  organism  described  by  Smith  as  a  form  in  the  development  of  in- 
testinal Coccidia,  the  acceptance  of  which  conclusion  would  place  the 
disease  among  the  coccidioses. 

The  term  "blackhead"  has  been  used  to  designate  a  numl)er  of  dis- 
eases of  fowls,  among  which,  in  addition  to  entero-hepatitis,  are 
cholera,  helminthiasis,  intestinal  coccidiosis,  and,  in  general,  any  dis- 
ease which  may  be  accompanied  by  dark  discoloration  of  the  comb  and 
wattles. 

Symptoms. — It  has  been  shown  that  entero-hepatitis  can  be  trans- 
mitted directly  from  diseased  to  healthy  turkeys,  natural  hifection  prob- 
ably taking  place  through  food  and  water  contaminated  with  the 
droppings  from  the  affected  animals.  At  the  expiration  of  the  incuba- 
tion period,  which  is  usually  within  one  month,  the  disease  is  initiated 
by  loss  of  appetite  and  a  drooping  listlessness  which  is  soon  followed 
by  diarrhea,  the  fluid  discharge  l)eing  yellowish  in  color  and  of  exceed- 
ingly offensive  odoi\  Weakness  and  emaciation  have  already  set  in, 
and  the  comb  and  wattles  show  th(>  blackish  discoloration  from  which 
the  disease  takes  its  name, — blackhead. 

Death  usually  occurs  after  a  course  of  from  five  to  eight  days.  The 
mortality  is  highest  in  young  animals,  among  which  it  is  estimated  to 
be  eighty  to  ninety  per  cent.  Adults  are  more  likely  to  recover,  though 
usually  only  after  a  long  period  of  emaciation  duiing  which  there  may 
be  a  relapse. 

Post-mortem  Appearance. — The  changes  observed  on  necropsj^  are 
those  of  necrotic  degeneration  of  the  cecal  mucosa  and  liver.  The  walls 
of  the  ceca  are  thickened,  the  nmcous  membrane  ulcerated  and  covered 
with  fibrous  memljranes  and  exfoliating  necrotic  tissue.  The  liver  is 
much  enlarged  and  shows  on  its  surface  numerous  yellowish  areas  with 
the  centers  softened.  These  areas  may  be  quite  small  or  up  to  15  mm. 
(5/8  of  an  inch)  or  more  in  diameter.  Other  portions  of  the  digestive 
tract  are  not  affected. 

Examination  in  hanging  drop  of  enuilsified  tissue  of  the  cecal  mucosa 
and  the  necrotic  foci  of  the  liver  will  reveal  the  amebae.  The  organisms 
found  in  the  liver  occur  as  rounded  or  oval  cells  measuiing  6-14  microns 
and  having  a  comparatively  small  nucleus.  Smith  concluded  from  his 
investigations  that  the  parasites  were  not  intracellular  but  lived  in  the 
tissue  spaces.  In  the  liver  they  are  thought  to  occupy  the  spaces  of  the 
necrosed  and  disappearing  liver  cells. 


826  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Control. — The  sick  animals  should  be  at  once  separated  from  those 
which  are  apparenth'  not  infected  and  the  pens  and  runs  subjected  to 
thorough  cleaning  up  and  disinfection  as  recommended  in  other  forms 
of  poultry  parasitism.  It  is  important  that  the  yards  be  kept  dry  and 
that  the  droppings  be  promptly  removed  and  so  disposed  of  that  thej^ 
cannot  be  a  source  of  reinfection. 

Treatment  is  of  little  value.  As  paUiative,  intestinal  antiseptics,  as 
eucalyptus  or  listerine,  may  be  tried. 

Amebic  Dysentery  in  Man. — This  is  a  disease  occurring  in  tropical 
and  subtropical,  and  at  times  in  temperate  regions,  the  cause  of  which 
is  regarded  bj'  pathologists  to  be  an  ameba, — Entamha  histolytica.  Ar- 
tificial production  of  amebic  dysentery  has  been  brought  about  in  dogs 
and  cats  by  rectal  introduction  of  human  feces  containing  the  amebae. 
It  has  been  shown  in  such  cases  that  the  parasites  invade  the  glandular 
crypts  of  the  intestinal  mucosa  from  which  they  penetrate  to  the  sub- 
mucosa  and  give  rise  to  a  hemorrhagic  enteritis.  In  its  further  course  the 
affection  is  accompanied  by  thickening  and  destructive  ulceration  of  the 
mucosa. 

The  diagnosis  of  amebic  dysentery  is  by  demonstration  of  the  ame- 
bae in  the  stools.  They  may  be  differentiated  from  Entameba  coli,  an 
intestinal  species  which  is  considered  to  be  a  harmless  commensal,  by 
their  definite  and  relatively  firm  ectoplasm  which  gives  a  rigid  character 
to  the  pseudopodia,  enabling  the  parasites  to  force  their  way  between 
the  epithelimn  of  the  crypts  and  into  the  more  deeply  lying  tissues.  The 
nucleus  of  E.  histolytica  varies  in  shape  and  position  with  the  activities 
of  the  cytoplasm;  it  has  little  chromatin,  and  no  nuclear  membrane  is 
apparent.  The  nucleus  of  E.  coli  is  usually  spherical  and  shows  little 
change  in  position. 

Class  II.    Flagellata  (Mastigophora) 

Protozoa  (p.  311). 

As  has  been  stated,  there  are  certain  forms  among  the  Rhizopoda  in 
which  the  pseudopodia  disappear  from  time  to  time  to  be  replaced  by 
one  or  more  flagella;  in  other  cases  there  maj^  even  be  permanent  fla- 
gella  contributing  to  the  pseudopodia  in  their  function  of  locomotion  and 
prehension.  Such  flagellate  rhizopods  are  transitional  to  the  Flagellata 
and  serve  to  prevent  the  drawing  of  a  sharp  line  of  demarcation  between 
the  two  groups  based  upon  the  possession  of  flagella.  In  general  it  maj^ 
be  said  of  the  Flagellata  that  they  are  permanently  flagellate,  the  fla- 
gella serving  for  locomotion  and  feeding.  Thej'  exhibit  a  great  diversity 
of  form  which  is  to  a  large  extent  correlated  with  the  number  and  loca- 
tion of  the  flagella.  A  degree  of  complexity'  is  exhibited  by  some  free- 
living  forms  in  the  possession  of  a  mouth  and  cytopharynx.  but  all  par- 


THE  PROTOZOAN  SUBGROUPS 


327 


asitic  forms,  and  most  of  those  which  are  free-hving,  obtain  their  nour- 
ishment by  absorbtion  through  the  general  surface  of  the  body. 

The  parasitic  flagellates  come  within  two  orders. — Spirochetida  and 
Trypanosomatida . 

Order  I.    Spirochetida 

Flagellata  (p.  326). 

The  spirochetes  are  of  somewhat  uncertain  position  because  of  in- 
complete knowledge  of  their  flagella  and  life  history.  They  multiply  by 
longitudinal  di\'ision,  or  it  may  be  by  transverse  division  as  do  bacteria, 
and  many  wiiters  have  placed 
them  with  the  latter  organisms. 
They  range  from  one  to  two 
hundred  microns  in  length,  and 
the  body  is  filamentous  and 
spiral  in  form  (Fig.  169).  Deli- 
cate flagella  may  be  present  at 
one  or  both  ends.  Nuclei  can- 
not be  distinctly  demonstrated ; 
the  nuclear  material  is  prob- 
ably distributed  as  granules 
throughout  the  protoplasm  as 
in  bacteria.  Motility  is  exhib- 
ited by  rotatory  movements, 
and  the  progression  may  be  in 
either  direction. 

Excepting  in  poultry,  the  spirochetes  are  not,  so  far  as  known,  seriously 
pathogenic  in  the  domestic  animals.  The  extreme  pathogenicity  of 
certain  spirochetes  in  man,  however,  indicates  the  disease-producing 
possibilities  of  the  group  and  rates  it,  potentially  at  least,  as  a  dangerous 
one  to  all  higher  animals. 


l-'iu.  IG'.).— Spirocheta  pallida  (after  Craw- 
ley, from  Doflein,  after  Sohaudinn,  Cir.  No.  194; 
Bu.  An.  Ind.,  U.  S.  Dept.  Agr.). 


Spirochetosis  of  Fowls 

This  disease  was  first  described  Ijy  Marchoux  and  Salimbeni  who, 
working  in  Brazil,  noted  that  special  varieties  were  more  susceptible 
and  suffered  more  severely  from  the  attack  than  common  fowls.  The 
condition  was  originalh-  termed  fowl  septicemia,  or  Brazilian  septicemia 
of  fowls,  and  is  now  considered  to  be  due  to  the  presence  of  the  spirochete 
Spirocheta  gallinanim  (S.  marchoiixi)  which  lives  in  the  l)lood.  is  15-20 
microns  in  length,  and  is  carried  from  host  to  host  l)y  the  tick  Arqas 
miniatus. 

The  investigators  above  mentioned  distinguish  an  acute  and  chronic 
form  of  the  disease,  the  former  characterized  by  emaciation,  drooping. 


3^28 


PARASITES  OF  THE  DOMESTIC  ANIMALS 


diarrhea,  and  anaemia.  Toward  the  end  weakness  has  so  far  advanced 
that  the  affected  birds  are  completely  helpless  and  lie  with  their  heads 
upon  the  ground.  Those  which  survive  are  said  to  be  immune  to  fur- 
ther attack.  The  spiroochete  sometimes  penetrates  the  red  blood 
cells;  it  has  also  been  found  in  the  eggs  and  in  the  embryonal  epithelium 
of  the  chick. 

It  is  not  known  with  certainty  that  the  disease  exists  in  this  country. 
It  is  not  unlikely,  however,  that  some  of  the  as  yet  obscure  diseases 


Fig.  170. — Hen  suffering  from  acute  spirochetosis  (after  Crawley,  from  Balfour,  Cir. 
No.  194,  Bu.  An.  Ind.,  U.  S.  Dept.  Agr.). 

of  poultry  may  be  found  to  be  due  to  members  of  the  spirochete  group, 
— a  sufficient  reason  for  mentioning  the  Brazilian  spirochetosis  here. 


Order  II.    Trypanosomatida 

Flagellata  (p.  326). 

A  number  of  classifications  have  been  proposed  for  these  organisms, 
Salmon  and  Styles  placing  them  in  the  order  Monadida  (Moore,  1906). 
Calkins  (1909)  classifies  them  as  follows:  Subphylum  Mastigophora; 
class,  Zoomastigophora;  subclass,  Lissoflagellata;  order,  Trypanosoma- 
tida; typical  genera,  Tiypanosoma  and  Trypanoplasma.  The  same 
author  thus  describes  the  order  in  tabulation:  "Organisms  of  elongate, 
usually  pointed  form,  and  of  parasitic  mode  of  life;  with  one  or  two 
flagella  arising  from  a  special  "motor"  nucleus,  and  with  an  undulating 
membrane  provided  with  myonemes  running  from  the  kinetonucleus 
to  the  extremity  of  the  cell;  one  of  the  flagella  is  attached  to  the  edge 


THE  PROTOZO.IN  SUBGROUPS  329 

of  this  membrane  throughout  its  length,  and  may  terminate  with  the 
membrane  or  be  continued  beyond  the  body  as  a  free  lash." 

All  species  of  the  genus  Trypanosoma  show  a  general  morphologic 
similarity.  In  general  thej^  may  be  said  to  measure  from  15-45  microns 
in  length,  including  the  flagellum,  and  1-5  microns  in  thickness.  As 
typical  of  the  group,  T.  theileri,  living  exclusively  in  the  blood  of  cattle, 
may  be  taken  for  brief  description.  The  body  is  spindle-shaped,  more 
or  less  serpentine,  and  pointed  at  the  ends,  from  one  of  which  there  pro- 
jects a  vibratile  flagellum.  The  flagellum  is  continued  as  a  marginal 
cord  toward  the  opposite  end  of  the  body  where  it  takes  origin  in  a 
minute  granule  (blepharoplast).  In  close  relation  to  this  granule  is  a 
deeply  staining  body  which,  because  of  its  connection  with  the  motile 
elements  of  the  cell,  has  been  designated  the  kinetonucleus.  Arising 
from  the  kinetonucleus,  the  flagellum  passes  along  the  body  on  the 
border  of  a  delicate  protoplasmic  membrane — the  undulating  mem- 
brane--toward  its  free  extremity.  Centrally  located  is  the  tropho- 
nucleus,  the  nucleus  concerned  with  the  vegetative  processes  of  the  cell. 
This  is  clearly  defined  and  usualh'  has  the  chromatin  in  the  form  of 
granules  of  definite  number.  The  endoplasm  is  granular  and  may 
appear  vacuolated.  Reproduction  in  the  blood  of  the  vertebrate  host 
is  by  longitudinal  division  following  division  of  the  blepharoplast, 
kinetonucleus,  and  trophonucleus.  In  some  cases  the  daughter  cells 
remain  together  for  a  longer  or  shorter  time  in  a  sort  of  rosette  forma- 
tion. 

The  members  of  the  genus  Trypanoplasma  (Cryptobia)  have  two 
flagella.  They  are  mostly  parasitic  in  fishes;  so  far  as  known  there  are 
no  species  which  attack  higher  animals. 

Transmission. — The  Trypanosoma  are  parasites  of  the  blood, 
IjTuph,  or  cerebrospinal  fluid  of  vertebrates,  and,  with  one  known  ex- 
ception, their  transfer  is  accomplished  by  the  intervention  of  an  inter- 
mediate carrier  which  is  either  essential  and  indirect,  or  mechanical 
and  direct.  In  the  former  case  a  blood-sucking  fly  becomes  infected 
by  feeding  upon  the  blood  of  an  animal  harboring  the  trypanosomes. 
In  the  body  of  the  fly  the  trypanosomes  undergo  certain  changes, 
probably  of  a  revitalizing  nature,  and  for  a  period  of  time  the  fly  remains 
noninfective.  When  this  period  has  elapsed  the  tiypanosomes  within 
the  fly  resume  their  ability  to  infect  any  host  whose  blood  is  reached  by 
the  piercing  mouth  parts  of  the  fly.  Furthermore,  such  flies  remain 
infective  for  an  indefinite  period,  probably  for  the  remainder  of  their 
lives. 

By  the  direct  or  mechanical  method  of  transfer  the  fly,  after  having 
bitten  an  infected  animal,  very  shortly  afterward  visits  a  healthy  one 
and  may  inoculate  it  directly  with  its  contaminated  proboscis.  If  the 
fly  draws  the  blood  of  a  sick  animal  and  then  successively  visits  two 


330  PARASITES  OF  THE  DOMESTIC  ANIMALS 

healthy  ones,  the  second  of  the  latter  will  not  usualty  contract  the 
disease.  This  is  due  to  the  fact  that  the  proboscis  of  the  fly,  charged 
with  the  trypanosomes  from  the  blood  of  the  sick  animal,  becomes 
cleaned  of  the  organisms  in  biting  the  first  of  the  healthy  ones.  Any 
biting  arthropod  may  transmit  by  the  direct  method;  the  abilit}'^  to 
infect  is  usually  limited  to  a  few  hours  from  the  time  of  biting  an  in- 
fected animal,  though  under  experimental  observation  it  has  been  re- 
tained for  a  considerably  longer  time  (see  Glossina,  p.  44). 

Nagana 

The  fundamental  work  upon  this  disease  was  carried  on  in  Zululand 
by  Bruce  who,  in  1895,  discovered  that  nagana,  or  the  so-called  tsetse 
fly  disease,  was  caused  by  a  trypanosome  which,  after  its  discoverer, 
has  been  named  Trypanosoma  brucei. 

"Nagana,  or  fly  disease,"  Bruce  writes,  "is  a  specific  disease  which 
occurs  in  the  horse,  mule,  donkey,  ox,  dog,  cat,  and  many  other  animals, 
and  varies  in  duration  from  a  few  days  or  weeks  to  many  months.  It 
is  invariably  fatal  in  the  horse,  donkey,  and  dog,  but  a  small  percentage 
of  cattle  recover.  It  is  characterized  by  fever,  infiltration  of  coagulable 
Ijaiiph  into  the  subcutaneous  tissue  of  the  neck,  abdomen,  or  extrem- 
ities, giving  rise  to  swelling  in  these  regions,  by  a  more  or  less  rapid 
destruction  of  the  red  blood  corpuscles,  extreme  emaciation,  often 
blindness,  and  the  constant  occurrence  in  the  blood  of  an  infusorial 
parasite." 

Nagana  is  a  Zulu  word  which,  according  to  Bruce,  refers  to  the  state 
of  depression  and  weakness  characteristic  of  the  disease. 

Nagana  exists,  particularly  in  low  and  humid  regions,  throughout 
Africa  with  the  exception  of  Tunis,  Algeria,  and  Morocco,  and  most  of 
the  countr.y  south  of  the  Tropic  of  Capricorn.  The  disease  is  supposed 
to  be  transmitted  mainly  the  by  the  tsetse  fly  Glossina  morsitans,  though 
other  species  probably  play  an  equal  part  in  this  respect.  Etiologic 
reference  to  nagana  has  already  been  made  in  the  review  of  the  work  of 
Bruce  under  the  suljject  of  Glossina  (p.  44)  and  need  not  be  repeated 
here. 

Plate  V. — Variou.s  Species  of  Trypanosoma.  1.  Trypanosoma  lewisi,  of  the  rat. 
2.  Trypanosoma  lewisi,  multiplication  rosette.  3.  Trypanosoma  lewisi,  small  form  re- 
sulting from  the  disintegration  of  a  rosette.  4.  Trypanosoma  brucei,  of  nagana.  5. 
Trypanosoma  equinum,  of  caderas.  6.  Trypanosoma  gambiense,  of  sleeping  sickness. 
7.  Trypanosoma  gambiense,  undergoing  division.  8.  Trypanosoma  theileri,  a  harmless 
trypanosome  of  cattle.  9.  Trypanosoma  transvaliense,  a  variation  of  T.  theileri.  10. 
Trypanosoma  avium,  a  bird  trypanosome.  11.  Trypanosoma  damonioe,  of  a  tortoise. 
12.  Trypanosoma  solese,  of  the  flat  fish.  13.  Trypanosoma  granulosum,  of  the  eel.  14. 
Trypanosoma  rajae,  of  the  skate.  15.  Trypanosoma  rotatorium,  of  frogs.  16.  Cryptobia 
borreli,  of  the  red-eye  (a  fish).  (After  Crawley,  from  Laveran  and  Mesnil;  Cir.  No.  194, 
Bu.  An.  Ind.,  U.  S.  Dept,  Agr.) 


5      ^^      6 


of     ^n 


332  PARASITES  OF  THE  DOMESTIC  ANIMALS 

Surra 

This  name  has  been  given  to  a  disease  of  horses,  camels,  and  dogs  of 
Asia  caused  by  Trypanosoma  evansi,  which  in  1880  was  found  by  Evans 
in  the  blood  of  affected  horses.  Surra  occurs  in  Southern  Asia,  the 
East  Indies,  the  Philippines,  Korea,  Australia,  and  among  the  drome- 
daries in  Northern  Africa  where  it  is  known  under  the  name  of  mbori. 

Symptoms. — In  its  constant  and  progressive  anaemia  and  cachexia 
the  disease  closely  resembles  nagana.  At  its  outset  there  is  a  rise  of  tem- 
perature which  in  some  cases  may  be  followed  by  an  urticarial  eruption. 
Edema  appears  under  the  skin  of  the  belly  and  limbs,  and  the  eyelids 
become  puffy  with  conjunctiva  congested.  The  appetite  is  usually  re- 
tained, but  in  spite  of  this  there  is  loss  of  flesh  and  strength.  Later  the 
appetite  is  lost,  there  is  great  weakness,  and  the  wasted  and  enfeebled 
animal  may  fall  and  be  unable  to  again  get  upon  its  feet. 

Course. — Horses  invariably  die  in  from  one  to  several  months  after 
the  onset  of  the  disease,  though  in  some  cases  death  may  occur  suddenly 
in  the  early  stages.  In  camels  the  disease  runs  a  much  longer  course. 
Cattle,  though  they  may  harbor  the  parasites  in  their  blood,  generally 
resist  the  disease. 

Infection. — A  specific  carrier  of  the  organism  causing  surra  is  not 
known.  Tsetse  flies  are  not  found  in  Asia,  but  it  has  been  determined 
that  the  stable  fly  {Stomoxijs  calcitrans)  and  the  horsefly  (Tabanus  stri- 
atus)  of  Asiatic  countries  can  transmit  the  disease  by  their  bite.  It  is 
believed  by  some  that  the  horsefly  is  the  principal  carrier.  So  far  as 
known  the  flies  carry  the  disease  from  animal  to  animal  directly  by  means 
of  contaminated  mouth  parts,  and  are  unable  to  infect  for  more  than 
one  or  two  days  after  having  drawn  the  blood  of  an  infected  animal. 

Mal  De  Caderas 

Mai  de  caderas  (disease  of  the  hip)  is  a  trypanosomiasis  occurring  in 
horses  throughout  the  greater  part  of  South  America,  caused  by  Ti^y- 
panosoma  equinum,  which  was  discovered  by  Elmassian  in  the  blood  of 
horses  in  Argentina  in  1901.  The  occurrence  of  the  disease  by  natural 
infection  is  almost  exclusively  among  horses  and  mules,  the  former  of 
which  are  the  more  susceptible.  A  number  of  other  mammals  may  be 
successfully  inoculated,  among  them  the  hog,  rabbit,  guinea  pig,  rat,  and 
mouse. 

Symptoms. — Following  a  statement  that,  owing  to  its  great  ravages 
in  certain  parts  of  South  America,  cattle  have  to  be  used  for  riding  purpo- 
ses, Laveran  and  Mesnil  (Trypanosomes  and  Trypanosomiases,  Eng- 
hsh  edition)  describe  the  symptons  of  the  disease  as  follows : 

"The  first  sign  of  the  disease  in  horses  is  wasting,  which  rapidly  pro- 


THE  PROTOZOAN  SUBGROUPS  333 

gresses  in  spite  of  a  good  appetite.  The  temperature  is  often  raised  to 
104°  to  105.8°  F.  After  a  varible  time  it  is  noticed  that  the  hind  quar- 
ters are  weak,  and  that  the  animal  drags  its  legs,  the  hoofs  grazing  the 
ground.  These  sj-mptons  increase  and  become  characteristic,  so  that 
when  the  animal  is  made  t  >  walk  it  staggers  along,  the  hind  quarters 
swaying  from  side  to  side.  On  account  of  this  sympton  the  name  liial 
de  caderas,  or  disease  of  the  hind  quarters,  has  been  given  to  the  disease. 
There  comes  a  time  when  the  animal  is  unable  to  stand;  if  in  the  stable, 
it  leans  up  against  a  wall  or  seeks  other  support;  if  in  the  open,  it  stag- 
gers and  falls.  After  thus  falling  to  the  ground  an  animal  may  still  live 
for  several  days  if  it  be  fed;  otherwise  the  inevitably  fatal  end  is 
hastened  bj'  inanition." 

Infection. — The  mode  of  natural  infection  is  not  as  yet  known.  The 
observed  fact  that  horses  separated  from  affected  animals  only  by  a 
fence  remain  healthy  in  spite  of  the  presence  of  piercing  flies,  would  indi- 
cate that  these  insects  are  not  the  transmitters.  Until  something  definite 
is  established  as  to  the  transmitting  agent,  no  certain  preventive  meas- 
ures can  be  adopted. 

DOURINE 

Dourine  is  an  infectious  disease  of  the  horse  and  ass  affecting  prima- 
rily the  genital  tract.  It  is  due  to  Trypanosoma  equiperdum,  transmitted 
from  animal  to  animal  in  the  act  of  copulation.  The  disease  is  vari- 
ously^ named  "maladie  du  coit,"  "  el  dourine,"  or  "  dourine,"  according 
to  the  country  in  which  it  is  found,  dourine,  which  is  from  the  Arabic  for 
"unclean,"  being  the  term  most  commonly  employed  for  it  in  the  United 
States.  It  is  supposed  to  have  been  introduced  into  Continental  Eu- 
rope early  in  the  nineteenth  century  by  horses  imported  for  breeding, 
especially  those  from  the  Orient  where  the  disease  has  long  existed. 

In  the  United  States  dourine  first  appeared  in  Illinois  where  it  was 
recognized  b}^  Dr.  W.  L.  Williams  in  1886.  The  source  of  the  infection 
was  found  to  be  imported  Percheron  stallion,  and  it  had  been  dissemi- 
nated for  some  time  before  the  true  nature  of  the  malady  became  known. 
By  the  application  of  rigid  preventive  measures,  the  disease  was  eradi- 
cated from  Illinois  in  1888,  but  it  had  been  carried  by  a  stallion  to  Ne- 
braska, where  an  investigation  of  an  outbreak  in  1892  by  an  inspector  of 
the  Bureau  of  Animal  Industry  revealed  that  upward  of  two  hundred 
mares  and  stallions  in  the  northwestern  part  of  that  state  were  aflfeeted 
with  the  disease.  Measures  taken  by  the  federal  authorities  brought  this 
outbreak  under  control  for  a  time,  but  a  few  3'ears  later  the  infection 
again  appeared  in  the  same  part  of  the  state.  In  1901  there  was  an  out- 
break in  the  Pine  Ridge  and  Rosebud  Indian  Reservations  of  South 
Dakota,  and  in  1903  the  disease  was  reported  in  Van  Buren  County, 
Iowa.    It  was  again  found  in  Taylor  County.  Iowa,  in  1911.    Thus  dour- 


334  PARASITES  OF  THE  DOMESTIC  ANIMALS 

ine  has  appeared  at  various  times  within  certain  Hmits  in  the  United 
States. 

Infection. — Dourine  is  a  pecuhar  trypanosomiasis  in  that  there  is 
no  intermediate  carrier  of  the  trypanosome  specifically  responsible  for 
it.  Like  the  spirochete  of  human  syphilis,  it  is  inoculable  by  contact,  the 
infection  usually  occurring  during  the  act  of  copulation,  though  reported 
cases  of  the  disease  in  geldings  and  in  mares  which  have  never  had  the 
stallion  would  indicate  that  its  transmission  is  not  entirely  by  copulation. 
It  may  be  artificially  transmitted  to  horses  and  to  other  susceptible 
animals,  as  dogs  and  rabbits,  by  inoculation  with  blood  from  animals 
affected.  Sexual  intercourse  is,  however,  by  far  the  most  common  means 
of  natural  infection,  the  trypanosome  reaching  the  blood  by  penetrat- 
ing the  intact  mucosa  of  the  genital  tract. 

Symptoms. — The  symptoms  of  dourine  as  given  by  John  R.  Mohler 
(Bureau  of  Animal  Industry,  Bulletin  No.  142,  1911)  are,  with  some 
omissions,  here  quoted. 

"There  are  many  variations  in  the  symptoms  of  dourine,  and  this  is 
particularly  true  of  the  disease  as  it  occurs  in  this  country.  Two  dis- 
tinct stages  may  be  noted  which  vary  somewhat  from  those  described 
in  textbooks,  but  probably  no  more  than  could  be  expected  when 
differences  of  climatic  conditions  and  methods  of  handling  are  taken 
into  consideration. 

"The  first  stage  chiefly  concerns  the  sexual  organs,  and  therefore 
differs  somewhat  in  the  male  and  female.  In  the  second  stage  symptoms 
indicating  an  affection  of  the  nervous  system  are  more  prominent  and 
are  not  dependent  on  the  sex  of  the  animal. 

"Following  a  variable  period  of  incubation  of  from  eight  days  to  two 
months,  there  is  seen  in  the  stallion  an  irritation  and  swelling  about 
the  penis  first  noticed  in  the  glans.  This  swelling  extends  throughout 
the  organ,  and  the  penis  may  be  continually  protruded  and  frequent 
ei-ections  noticed.  The  edematous  swelling  also  involves  the  groin, 
with  enlargement  of  the  adjacent  inguinal  glands,  and  extends  forward 
along  the  abdomen.  In  a  few  days  small  vesicles  or  blisters  appear  on 
the  penis,  which  break,  discharging  a  yellowish  serous  fluid  and  leaving 
irregular  raw  ulcers.  Where  primary  ulcers  are  in  proximity  to  each 
other  there  is  a  marked  disposition  to  coalesce,  a  large  raw  surface  with 
irregular  border  resulting.  The  ulcerative  process  may  form  a  wound 
extending  almost  entirely  around  the  penis.  The  ulcers  show  a  tendency 
to  heal  rapidly,  leaving  white  cicatrices  which  are  permanent.  In  some 
cases  the  urinary  meatus  is  very  red  and  swollen,  and  according  to  some 
observers,  especially  European,  more  or  less  thick  catarrhal  exudate 
is  discharged  from  its  oriface.  This  condition,  however,  has  been  rarely 
seen  in  cases  in  this  country,  a  more  or  less  continuous  dripping  from 
the  urethra  of  a  yellowish  serous-like  discharge  alone  being  present. 


THE  PROTOZOAN  SUBGROUPS  335 

The  stallion  retains  his  full  genetic  instinct  and  becomes  veiy  amorous 
when  brought  in  the  vicinity  of  mares.  If  allowed  access  to  mares  in 
season,  service  is  often  impossible,  due  to  the  fact  that  a  complete 
erection  of  the  penis  does  not  occur.  The  testicles  may  be  involved  and 
tender  to  pressui'e,  and  abscess  formation  may  occur  with  sloughing. 

"In  the  mare  the  first  s>nnptoms  may  be  so  slight  as  not  to  be  noticed 
by  the  owner.  The  disease  being  the  result  of  copulation,  begins  with 
swelling  and  inflannnation  of  the  vulva  and  vagina.  The  labia  are 
continuall}'  everted,  exposing  the  clitoris,  which  is  constantly  in  a  state 
of  erection.  There  will  also  be  a  muco-purulent  discharge  like  that 
coming  from  the  penis  of  the  male,  which  may  be  slight  or  profuse  in 
quantity.  The  mare  will  switch  the  tail,  appear  uneasy,  and  urinate 
frequently.  Shortly  papules  and  vesicles  appear  on  the  external  vulva, 
as  well  as  on  the  mucosa  of  the  vulva  and  vagina.  These  vesicles  soon 
rupture,  but  before  doing  so  the  contents  undergo  a  change  from  a 
transparent  to  a  purulent  fluid.  The  rupture  of  these  pustules  is  the 
initial  stage  in  the  formation  of  deep,  angry  ulcers.  These  ulcers  show 
a  tendency  to  heal  rapidly,  but  invariably  leave  a  cicatrix.  On  the  dark 
skin  of  the  external  vulva  the  scars  will  always  be  white.  This  de- 
pigmentation is  permanent. 

'"Sometimes,  especially  in  the  mare,  the  above-described  lesions  tend 
to  disappear  gradually,  and  in  case  the  mare  is  not  served  again  the 
disease  may  remain  in  abeyance  for  months  or  a  j-ear.  The  apparent 
recovery,  however,  is  not  permanent,  and  any  excessive  work  or  excite- 
ment may  set  up  the  disease  anew.  In  case  an  affected  mare  conceives, 
she  is  liable  to  abort  at  any  time  during  her  term  of  pregnancy.  When 
the  fetus  is  carried  to  full  term,  it  occasional^  is  a  weak  or  imperfectly 
developed  foal,  but  in  this  country  many  fine  colts  have  been  born  to 
affected  mares. 

"The  nervous  or  constitutional  disturbances  of  the  second  stage  may 
not  come  on  for  months  or  even  a  year  after  the  appearance  of  the  local 
lesions,  and  are  similar  in  both  male  and  female.  They  consist  of  a 
general  nervous  disorder  with  staggering,  swaying  gait,  especially  in 
the  hind  limbs.  The  animal  becomes  extremeh'  emaciated,  particularly 
in  the  hind  quarters,  and  the  abdomen  assumes  a  "tucked-up"  appear- 
ance. The  first  indication  of  paralysis  will  be  noted  in  traveling,  when 
the  animal  fails  to  pick  up  one  of  the  hind  feet  as  freely  as  the  other. 
There  is  a  tendency  to  drag  the  foot  partially.  This  condition  may 
shift  from  one  hind  foot  to  the  other,  or  both  may  become  affected 
simultaneously.  Twitching  of  the  superficial  muscles  has  been  noticed 
in  several  instances.  Urticarial  eruptions  or  plaques  may  break  out 
over  various  parts  of  the  body,  and  there  may  be  noticed  pruritus  of 
the  skin,  which  causes  the  animal  to  rub  itself  frequently.  The  tem- 
perature of  the  animal  seldom  goes  above  101°  or  102°  F.    When  the 


336  PARASITES  OF  THE  DOMESTIC  ANIMALS 

paralysis  of  the  hind  Hmbs  starts  to  appear,  it  usually  progresses  rapidly, 
the  horse  goes  down,  is  unable  to  rise,  and  dies  in  a  short  time  from 
nervous  exhaustion." 

Control. — As  dourine  is  transmitted  and  spread  only  by  copulation, 
its  eradication  is  a  less  difficult  problem  than  in  trypanosomiases  which 
may  be  carried  by  flies.  So  little  benefit  is  to  be  derived  from  medicinal 
treatment  that  in  this  country,  where  the  disease  has  appeared  only 
in  restricted  areas,  it  is  not  advisable.  While  cure  may  be  possible, 
an  apparently  cured  animal  may  carry  the  trypanosomes  for  months 
in  the  sexual  organs,  and  relapses  are  likely  to  occur.  In  areas  where 
the  disease  appears  measures  of  eradication  must  be  based  upon  the 
prevention  of  infected  animals  from  breeding. 

To  confine  the  losses  to  the  minimum,  therefore,  the  prompt  castration 
of  affected  stallions  and  the  destruction  of  diseased  mares  is  essential. 
Spaying  of  such  mares  is  not  a  sufficient  precaution  from  the  fact  that 
they  may  be  sold  and  an  attempt  made  to  breed  them,  thus  infecting 
the  stallion  and  through  this  source  spreading  the  disease.  Restrictions 
in  the  movement  of  horses  in  infected  districts  and  frequent  reinspection 
are  further  state  and  federal  measures  for  confining  an  outbreak  so  far 
as  possible  to  its  original  limits. 

Trypanosoma  americanum. — This  trypanosome  is  found  in  cultures 
of  blood  from  healthy  American  cattle.  It  deserves  mention  here  on 
account  of  its  common  occurrence,  though  it  appears  to  be  harmless. 
A  report  by  Crawley  upon  his  extended  study  of  this  organism  will  be 
found  in  Bureau  of  Animal  Industry  Bulletin  No.  145  (1912). 

Class  III.    Sporozoa 

Protozoa  (p.  311). — The  Sporozoa  are  all  parasitic.  Though  without 
motile  organs,  they  are  capable  of  moving  from  place  to  place,  in  some 
cases  by  means  of  pseudopodia.  Reproduction  is  mainly  by  spore 
formation,  either  asexual  or  sexual.  There  are  a  number  of  forms, 
however,  in  which  simple  reproduction  occurs,  and  the  group  comprises 
organisms  with  life  histories  as  yet  not  fully  known.  The  Sporozoa, 
therefore,  is  a  division  to  be  regarded  as  provisional,  containing  at  pres- 
ent organisms  which  when  their  life  histories  are  fully  made  out  may 
be  more  accurately  placed  with  other  divisions  of  the  Protozoa. 

Based  upon  the  belief  that  the  Sporozoa  are  polyphyletic;  that  is  that 
all  have  not  the  same  ancestral  history,  they  have  been  placed  in  two 
divisions, — Telosporidia  and  Neosporidia,  the  former  regarded  as 
descended  from  the  flagellates,  the  latter  from  the  rhizopods.  Of  the 
Telosporidia  but  two  orders  are  to  be  considered  here, — Coccidia  and 
Hemosporidia.  The  Neosporidia  has  one  order, — Sarcosporidia,  con- 
taining parasites  of  domestic  animals. 


THE  PROTOZOAN  SUBGROUPS  337 

Order  I.    Coccidia 

Sporozoa  (p.  336). — The  Coccidia  are  cytozoic  or  cell-infesting  para- 
sites, attacking  epithelium  of  in\-ertebrate  and  vertebrate  animals.  Re- 
production is  by  schizogony  and  by  sporogony,  the  asexual  and  sexual 
generations  alternating  in  the  life  cycle.  In  species  parasitic  to  domestic 
animals  the  fertilized  cell  produces  sporoblasts  covered  by  a  sporo- 
cyst  membrane. 

Life  History. — The  life  cycle  is  similar  to  that  of  the  malaria  organ- 
isms except  that  no  arthropod  intermediate  host  is  required  for  the 
sexual  reproduction.  Infection  with  Coccidia  is  with  the  encysted  stage 
(oocj'st)  by  way  of  the  mouth.  Hence  the  parasites  are  almost  exclu- 
sively found  in  the  epithelium  of  the  aliment ry  canal  and  organs  con- 
nected with  it.  Reaching  the  stomach  and  duodenum,  the  oocyst  is 
acted  upon  by  the  digestive  juices  and  the  sporozoites  contained  in  the 
cyst  are  hberated.  These  enter  the  epithelial  cells  of  the  mucosa.  Within 
the  cells  they  lose  their  spindle  form  and  enter  the  stage  of  the  tro- 
phozoite in  which  they  grow  to  a  size  depending  somewhat  upon  that 
of  the  invaded  cell.  By  the  process  of  schizogony  the  trophozoite  di- 
vides into  a  number  of  small  protoplasmic  masses  which  are  the  mero- 
zoites  or  asexually  formed  spores.  These  invade  other  cells  and  in  the 
same  manner  grow  into  another  generation  of  merozoites.  Bj^  many 
repetitions  of  this  cycle  a  large  number  of  cells  are  invaded  and  de- 
stroyed, and  the  death  of  the  host  animal  may  follow  as  a  result.  After 
a  number  of  asexual  cycles  some  of  the  merozoites  do  not  grow  and  di- 
vide into  another  generation  of  merozoites,  but  develop  into  stages  which 
begin  the  sporogonous  or  sexual  cycle.  In  this  process  the  female  tro- 
phozoite instead  of  dividing  develops  into  an  egg  or  macrogamete.  The 
male  trophozoite,  by  division,  forms  minute  male  repi-oductive  elements 
or  microgametes.  By  their  motility  the  microganietes  reach  and  fer- 
tilize the  macroganietes  which,  becoming  surrounded  by  a  resistant 
membrane,  arrive  at  the  stage  of  the  oocyst.  Within  the  oocj'st  a  num- 
ber of  spores  may  be  formed,  each  inclosed  in  a  protecting  membrane 
and  constituting  a  sporocyst.  By  division  each  sporocyst  forms  two 
or  more  sporozoites,  and  thus  the  sexual  cycle  is  completed.  Where  the 
parasites  are  in  the  epithelium  of  the  alimentary  tract  or  its  comaiiu- 
nicating  organs,  the  oocysts  pass  to  the  exterior  with  the  feces.  In  other 
cases  it  may  be  that  they  can  only  reach  the  outside  after  the  death  and 
disintegration  of  the  host. 

The  effect  of  coccidiosis  upon  the  animal  is  brought  about  by  the  ex- 
tensive destruction  of  cells  resulting  from  the  repeated  production  of 
merozoites  by  schizogny.  This  progressive  reproduction  and  cell  de- 
struction would  in  every  case  result  in  the  death  of  the  animal  were  it 
not  that  the  number  of  schizogonous  generations  is  limited.    The  cell 


Plate  VI,  Fig.  2. 


Plate  VI. — Fig.  1. — Percheroii  stallion,  showiiifi  condition  at  the  time  of  purchase. 
Fig.  2.  Same  stallion  after  dourine  luul  developed.  Spot.s  on  side  and  croup  give  location 
of  plaques.     (After  Mohler,  Bui.  Xo.  142,  Bu.  An.  Ind.,  U.  S.  Dep  Agr.). 


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Plate  VII,  Fig. 


Plate  VII,  Fig.  2. 


Plate  VII. — Fig.  1. — Perclicron  marc,  showing  chronic  dourinc.  Observe  the  "tucked 
up"  abdomen  and  emaciation,  the  mare  having  lost  over  700  pounds  in  the  previous  four 
months.  Fig.  2. — A  mare  in  the  last  stage  of  dourine.  Notice  the  position  of  the  off  hind 
foot  and  the  straightened  hock  joints.  (After  Mohler,  Bui.  No.  142,  Bu.  An.  Ind.,  U.  S. 
Dept.  Agr.). 


342  PARASITES  OF  THE  DOMESTIC  ANIMALS 

destruction  ceases  with  the  beginning  of  the  sporogonous  C3'cle,  and,  if 
the  acute  stage  of  the  disease  is  survived,  the  animal  tends  to  recover, 
the  destroyed  cells  being  replaced  more  or  less  completel}^  by  newlj' 
formed  ones.  Thus  it  maj^  be  said  that  the  disease  is  self-limiting. 
Eimeria  stiedae. — Coccidia  (p.  337). — This  coccidian,  also  known 
as  Coccidium  oviforme  and  C.  cuniculi,  is  the  species  commonlj^  found 
in  the  Hver  of  domestic  rabbits.  Most  frequently  it  attacks  the  epithe- 
lium of  the  bile  ducts  where  it  causes  destruction  of  cells  and  pathologic 
changes  in  the  Uver  by  which  the  secretion  of  bile  is  reduced.  The  con- 
dition affects  rabbits  seriously  and  deaths  occur  as  a  result  of  it. 

Eimeria  stiedce  is  considered  by  some  authors  as  a  cause  of  coccidiosis 
in  man. 

Diplospora  bigemina  (Isospora  bigemina).  Coccidia  (p.  337). — In 
a  report  upon  their  work  with  this  coccidian  Hall  and  Wigdor  (Journal 
of  the  American  Veterinary  Medical  Association,  April,  1918)  state  that 
in  two  hundred  dogs  examined  at  Detroit,  Michigan,  it  was  found  in 
fifteen,  or  slightly  over  seven  per  cent.  From  this  finding  they  suggest 
that  the  parasite  may  be  more  common  in  American  dogs  than  our  pres- 
ent lack  of  information  would  indicate. 

In  reference  to  the  pathogenesis  of  Diplospora  bigemina,  these  au- 
thors may  be  further  quoted  from  the  same  article  as  follows : 

"As  regards  the  pathological  significance  of  D.  bigemina,  we  have 
but  Httle  information,  but  the  following  notes  may  serve  some  purpose: 
Dog  No.  130  presented  a  clinical  picture  of  distemper  and  died  of  pneu- 
monia, probably  due  in  part  to  distemper  and  partlj'  to  an  accident 
in  drenching.  The  small  intestine  showed  diffuse  hemorrhagic  points, 
most  pronounced  in  the  ileum,  especially  the  lower  ileum  near  the  valve. 
Scrapings  of  the  mucosa  showed  the  coccidia  to  be  most  abundant  in  the 
ileum,  less  so  in  the  jejunum  and  least  so  in  the  duodenum.  These 
findings  of  increasing  numbers  of  coccidia  with  increasing  severity 
of  lesions  may  be  correlated,  but  in  the  absence  of  sections  indicating 
the  relation  of  the  coccidia  to  the  hemorrhage,  we  do  not  care  to  hazard 
a  definite  opinion.  Dog  No.  173  showed  numerous  fine  petechiae  in  the 
intestinal  mucosa,  and  these  were  especally  numerous  in  the  Peyer's 
patches,  giving  these  a  uniformly  dark  appearance.  No  sections  were 
made  and  this  dog  had  shown  no  oocysts  in  the  feces  for  fortj^'-five  days. 
Dog  No.  127  showed  innumerable  pinpoint  petechiae  in  the  ileum,  but 
it  would  be  unsafe  to  draw  conclusions  based  on  this  one  dog,  as  the 
animal  figured  in  other  experiments.  The  intestine  of  dog  No.  223  was 
macroscopically  normal  except  for  the  presence  of  hook-worm  petechiae. 
In  view'of  the  fact  that  coccidia  are  destructive  to  epithelial  tissue  and 
that  some  species  fairly  closel}^  related  to  D.  bigemina  are  known  to  be 
highly  pathological,  it  would  seem  reasonable  to  suppose  that  D.  big- 
emina might  be  distinctly  pathological  at  times,  though  the  apparent 


THE  PROTOZOAN  SUBGROUPS  343 

?i;ood  health  and  lack  of  post-mortem  lesions  in  other  do^s  makes  it  cer- 
tain that  it  often  does  no  visible  damage." 

Coccidium  zurni.  Coccidia  (p.  337). — Red  dysentery  of  cattle  is 
attributed  to  this  coccidian.  The  disease  occurs  in  Europe,  generally 
among  young  animals  as  an  enzootic.  The  attack  of  the  parasites  upon 
the  cells  of  the  intestinal  mucosa  causes  extei^sive  hemorrhage,  the  red 
diarrhea  resulting  fi-om  the  mixture  of  the  blood  with  the  feces.  Mild 
cases,  particularly  in  adult  animals,  ma\'  soon  recover.  Severe  cases, 
occurring  particularly  in  young  animals,  may  run  a  hyperacute  course 
and  terminate  fatally  within  two  da\'S,  or  an  acute  course  of  five  to  ten 
days  may  precede  this  termination. 

In  the  report  of  the  Committee  on  IVIedicine  and  Surgery  submitted 
at  the  meeting  of  the  Pennsylvania  State  A'eterinary  ^Vledical  Associa- 
tion, held  in  January,  1918,  Dr.  W.  J.  Uentz,  of  the  University  of  Penn- 
sylvania, called  attention  to  cases  of  intestinal  coccidiosis  of  cattle 
which  had  come  under  his  ol:)servation  in  the  State  of  Delaware.  His 
report  as  published  in  the  Journal  of  the  American  \'eterinary  ]\Iedical 
Association  for  November,  1918,  follows: 

"Was  asked  to  consult  with  a  vetermarian  on  an  interesting  condition 
in  a  herd  of  grade  Holsteins.  Owner  had  lost  four  or  five  heifers  over  a 
period  of  about  two  weeks,  ranging  in  age  from  six  months  to  eighteen 
months.  All  presented  similar  s\anptoms.  There  was  first  noticed  a 
serous,  fetid,  black  diarrhea.  Fever  was  rarely  in  evidence  at  any  time. 
The  diarrhea  after  a  few  days  changed  to  mucus,  with  the  passage  of 
blood  clots  with  the  mucus  and  feces  from  time  to  time.  Straining  was 
very  marked.  Appetite  somewhat  impaired  but.  nevertheless,  partook 
of  some  food,  but  finally,  in  about  six  to  eight  days,  became  very  dull, 
refused  food,  emaciated  rapidly,  rectum  became  relaxed,  temperature 
subnormal,  pulse  hardly  perceptible,  and  these  sjnnptoms  of  collapse 
were  soon  followed  by  death.  On  arrival  at  the  farm  found  six  to  eight 
calves  and  one  adult  cow  presenting  some  of  the  s\nnptonis  mentioned, 
and,  inasmuch  as  one  was  about  to  die,  it  was  destroyed  and  posted. 
Lesions  were  confined  to  the  large  intestine.  No  apparent  pathological 
change  in  anj-  other  organ.  The  mucous  membrane  of  the  large  in- 
testine, which  was  almost  empty,  was  red  brown  in  color,  soft  and 
spong}',  and  everywhere  coated  with  a  bloody  nmcus.  The  back  of  the 
knife,  after  the  intestine  was  slit  open,  was  passed  over  the  mucous 
surface  and  the  bloody  mucus  scraped  off,  when  it  was  noticed  that 
large  superficial  ulcers,  white  in  color,  and  about  the  size  of  one's  palm, 
were  present  throughout  the  whole  extent  of  the  large  intestine  from 
the  cecum  to  the  anus.  Some  of  the  mucous  patches  were  scraped  off 
and  collected  in  a  bottle,  also  some  of  the  blood  and  feces.  On  micro- 
scopic examination,  coccidia  were  detected.  A  diagnosis  of  "intestinal 
coccidiosis,"   or   "red  dvsentery,"   was  therefore  made.     Treatment 


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THE  PROTOZOAN  SUBGROUPS  345 

Plate  VIII. — Coccidian  Life  Cycle. — Fig.  1.  1.  Sporozoite  released  in  intestine  of 
host.  2.  Penetration  of  sporozoite  into  epithelial  cell.  3,  4.  Growth  of  sporozoite  into 
trophozoite.  5,  6,  7.  Schizogonous  cycle.  Nuclear  division,  followed  by  division  of 
entire  trophozoite  into  a  large  number  of  merozoites.  8.  Free  mcrozoites,  which  for  an 
indeterminate  number  of  generations  merely  repeat  the  schizogonous  cycle,  behaving 
precisely  as  do  the  sporozoites.  Eventually,  however,  the  sporogonous  cycle  is  initiated, 
which  proceeds  as  follows:  9a.  Undifferentiated  female  cell.  9b.  Undifferentiated  male 
cell.  10a.  Differentiated  female  cell.  10b.  Differentiated  male  cell.  11,  12.  Formation 
of  the  microgametes,  one  male  cell  producing  many  microgametes.  13a.  Macrogamete. 
One  female  cell  produces  but  one  macrogamete.  13b.  Ripe  microgamete.  14.  Fertiliza- 
tion. 15,  16,  17.  The  zygote.  18.  Beginning  of  spore  formation.  19.  Completion  of 
spore  formation.  20.  Formation  of  the  sporozoites  within  the  spores.  21.  Release  of  the 
sporozoites  in  the  intestine  of  the  host.  Fig.  2. — Introduced  for  comparison  with  the 
more  typical  cycle  shown  in  Fig.  1.  Here  the  parasite  penetrates  and  comes  to  rest  in  the 
nucleus  instead  of  the  cytoplasm,  and  there  is  se.xual  differentiation  in  the  schizogonous 
cycle  as  well  as  in  sporogony.  (After  Crawley,  from  Mense's  "Handbuch,"  after 
Schaudinn,  Cir.  No.  194,  Bu.  An.  Ind.,  U.  S.  Dept.  Agr.). 

suggested:  Pearson's  creolin  well  diluted  with  milk  or  water,  also  large 
doses  of  camphorated  tincture  of  opium,  and  rectal  injections,  using 
garden  hose  and  funnel,  of  a  two  per  cent,  creolin  solution,  alternating 
night  and  morning  with  a  one  per  cent,  alum  solution.  A  week  later 
received  word  that  all  were  doing  nicely  and  no  deaths." 

In  Europe  outbreaks  of  red  dysentery  similar  to  that  of  cattle  have 
occurred  in  sheep. 

CocciDiAL  Enteritis  of  Chicks 

The  use  of  the  name  "white  diarrhea"  for  this  coccidiosis  tends  to  its 
confusion  with  bacillary  white  diarrhea,  which  is  a  fatal  septicemia  of 
chicks  caused  by  Bacterium  pulloruni.  Coccidial  enteritis  or  coccidiosis 
of  chicks  is  caused  hyEimeria  avium  (Coccidium  tenelhim),  which  attacks 
the  epithelium  of  the  intestinal  mucosa,  usually  that  of  the  ceca.  Occa- 
tionally  the  infection  is  found  in  other  organs.  The  disease  is  usually 
seen  in  chicks  from  two  to  ten  weeks  old. 

Symptoms. — The  symptoms  are  merely  suggestive  of  coccidiosis  as 
they  do  not  materially  differ  from  those  of  some  other  diseases  of  poul- 
try. The  affected  chicks  droop  and  are  inclined  to  stand  about  by  them- 
selves with  eyes  closed  and  feathers  ruffled.  In  most  all  cases  there  is  a 
diarrhea  with  whitish-colored  discharge  which  stains  and  mats  the 
feathers  below  the  vent;  a  bloody  diarrhea  gives  evidence  of  coccidial 
infection.  If  the  discharge  is  examined  under  the  microscope  large 
numbers  of  circular  or  slightly  oval  oocysts  may  be  found.  Death  usually 
occurs  after  a  course  of  three  to  four  da3'S. 

Post-morten  Appearance. — Post-mortem  examination  reveals  the 
ceca  much  enlarged.  Their  contents  may  be  normal  or  they  may  be 
packed  with  a  yellowish  white  or  bloody  semiliquid  material.  The 
conclusion  that  the  chicks  are  not  infected  with  coccidia  should  not  be 
made  from  the  absence  of  enlarged  ceca,  as  occasionally  there  is  no 


346  PARASITES  OF  THE  DOIMESTIC  ANIMALS 

enlargement  of  these  organs  nor  abnormal  appearance  of  their  contents. 
Not  infrequently  the  enteritis  involves  the  entire  length  of  the  intestines. 
For  a  positive  diagnosis  microscopical  examination  of  the  intestinal 
contents  or  of  the  sectioned  intestinal  wall  is  necessary.  Spreads  of 
scrapings  from  the  cecal  mucosa  examined  under  the  microscope  will 
reveal  epithelial  cells  much  distended  by  the  development  of  the  par- 
asites within  them.  It  is  as  a  result  of  this  invasion  that  the  cells  finally 
break  down  and  separate  from  the  underlying  stroma  to  become  a  part 
of  the  pasty  catarrhal  exudate  which  characterizes  the  fecal  discharge. 

Infection. — Though  the  fatalities  are  usually  among  the  young 
chicks,  the  coccidian  which  causes  the  disease  may  be  found  in  chickens 
of  all  ages  and  it  ma}^  be  spread  from  this  source.  Infection  is  by  food 
and  ingested  soil  or  water  contaminated  by  droppings  which  contain 
the  cysts.  It  has  been  demonstrated  that  the  cysts  may  remain  infective 
for  a  year  or  more,  therefore  chickens  may  become  infected  if  allowed 
access  to  yards  where  those  harboring  the  parasites  were  kept  the  year 
previous. 

Control. — There  are  no  drugs  which  have  been  found  to  be  of  value 
in  treating  the  disease,  therefore  control  is  the  essential  consideration  in 
contending  with  it.  Morse  states  (Bureau  of  Animal  Industrj^  Cir- 
cular No.  128,  1908)  that  this  must  begin  with  the  eggs  used  for  hatching. 
"These,"  he  writes,  "should  be  thoroughly  and  antiseptically  cleaned 
bj^  wiping  in  ninety-five  per  cent,  alcohol.  If  artificial  incubation  is 
used  (and  in  this  method  lies  the  great  hope  of  success),  the  incubator, 
if  used  before,  should,  previous  to  receiving  the  eggs,  be  carefully  washed 
with  antiseptic  solutions  and  exposed  to  the  sun.  The  egg  tray  should 
be  scalded  or  flamed.  The  floor  of  the  nursery  should  be  movable,  so 
that  it  may  be  taken  out  and  sterilized,  and  if  made  of  burlap  the  old 
piece  should  be  torn  off  and  a  new  piece  mounted  on  the  sterilized  frame. 
The  same  precautions  should  be  used  with  the  brooders.  The  soil  to 
which  the  chicks  have  access  should  be  well  covered  with  lime,  dug  up, 
and  exposed  to  the  drying  effects  of  the  sun  and  air.  If  natural  in- 
cubation is  practiced  the  hen  for  a  week  or  two  before  being  set  should 
be  treated  with  one-quarter  to  one-half  grain  doses  of  sulphate  of  iron 
daily,  with  occasionally  an  active  purgative,  such  as  calomel,  one  grain, 
or  castor  oil,  one-half  teaspoonful  containing  five  to  ten  drops  of  tur- 
pentine. The  eggs,  cleansed  as  directed  above,  should  be  placed  in  a 
perfectly  fresh  nest,  which  may  be  sprinkled  from  time  to  time  with  a 
little  hme.  After  hatching,  the  hen  with  her  chicks  should  be  placed 
upon  ground  that  has  been  thoroughly  sterilized,  as  described  above, 
and  at  least  every  few  days  moved  to  fresh  ground  which  has  been 
treated  in  the  same  way  and  from  which  all  chickens  have  been  de- 
barred." 

Further  preventive  measures  are  the  removal  of  visibly  sick  chicks 


THE  PROTOZOAN  SUBGROUPS  347 

from  the  flock,  either  keeping  them  isolated  or  killing  and  burning  them. 
It  is  better  to  put  all  of  the  chickens  on  new  ground  if  possible,  other- 
wise the  ground  should  be  covered  with  lime  and  spaded  so  that  it  may 
be  exposed  to  the  drying  effect  of  the  sun  and  air.  All  litter  and  nesting 
should  be  burned  and  a  thorough  cleaning  up  of  the  quarters  followed 
by  the  application  of  a  strong  disinfectant  solution.  After  drying, 
the  floors  may  be  protected  from  rccontamination  somewhat  b,y  covering 
them  with  shavings,  chopped  bedding,  or  other  absorbant  material, 
which  is  to  be  cleaned  up  and  burned  dail}'.  Boards  should  be  placed 
beneath  the  roosts  to  receive  the  droppings  for  convenient  daily  removal. 
Contamination  of  feeding  and  drinking  vessels  can  in  a  measure  be  pre- 
vented b}^  elevating  them  somewhat  from  the  grountl.  They  should  at 
all  times  be  kept  clean;  daily  treatment  with  scalding  water  or  flaming 
followed  by  exposure  to  the  sun  will  do  much  to  eliminate  the  soiu'ce 
of  the  infection. 

Order  II.  Hemosporidia 

Sporozoa  (p.  336). — The  Hemosporidia  are  Sporozoa  which  dwell  in 
the  blood  where  they  invade  the  corpuscles,  hence  are  cytozoic.  Flag- 
ellated stages  appear  in  their  life  history,  and  many  protozoologists 
suspect  that  the  entire  group  has  been  evolved  from  the  flagellated 
Protozoa.  Comparing  the  life  history  of  the  malaria  organisms  (p.  318) 
with  that  of  the  Coccidia  (p.  337)  a  distinct  difference  will  be  noted  in 
the  method  of  infection,  the  hemosporidian,  as  is  true  of  others  of  the 
group,  being  transmitted  from  the  blood  of  one  animal  to  that  of  an- 
other by  means  of  a  known  intermediate  host,  while  the  Coccidia  infect 
directly,  usually  by  food  or  water  bearing  the  cysts.  In  diseases  caused, 
by  Hemosporidia,  the  infection,  due  to  the  activities  of  the  intermediate 
host,  is  more  widel}^  disseminated,  and  large  numbers  of  animals  may 
be  seriously  and  fatally  attacked.  As  blood  parasites,  therefore,  the 
Hemosporidia  may  be  rated  with  the  tiypanosomes  in  pathologic  im- 
portance. 

Texas  Fever 

Tick  fever.  Splenic  fever. 

Smith  and  Kilbourne  in  1893  foimd  small  parasites  in  the  red  blood 
corpuscles  of  cattle  suffering  with  Texas  fever.  Due  to  their  frequent 
occuri-ence  in  pairs,  the}'  were  given  the  specific  name  higeminum,  and  the 
genus  was  named  Pyrosoma.  The  later  generic  name  Piroplasma  was 
derived  from  their  often  assuming  a  pear-like  form,  and  the  name  now 
generalh'  used  for  the  hemosporidian  causing  Texas  fever  is  Piroplasma 
higeminum  (Fig.  171). 

The  medium  by  which  the  organism  is  transmitted  is  the  cattle  tick 
Margaropus  annulafus.  which  crawls  upon  its  host  as  a  larva,  attaches, 


348  PARASITES  OF  THE  DOMESTIC  ANIMALS 

and  here  undergoes  its  complete  development.  (Ref .  Margaropus  annul- 
atus,  Life  History,  p.  148.)  For  a  number  of  days  following  her  fer- 
tilization the  female  tick  engorges  with  the  blood  of  her  host  and  then 
drops  to  the  ground  where  a  few  clays  later  she  deposits  her  eggs  and, 
having  completed  her  cycle,  soon  dies.  The  parasites  contained  in  the 
blood  upon  which  the  tick  has  fed  reach  the  eggs  and 
are  present  in  the  larval  ticks  when  these  are  hatched. 
Thus  the  larvae  have  the  power  to  infect  any  susceptible 
animal  to  which  they  attach. 

In  the  first  stage  of  development  after  gaining  the 
circulation  the  piroplasma  is  within  the  red  corpuscle 
as  a  single  body  near  the  corpuscle's  margin.  Later  it 
Piroplasma^  Tig-  "^^^^i^^^^s  into  two  bodics  which  remain  slightly  connected 
eminum  (after  by  a  Small  filament.  A  single  corpuscle  may  contain  as 
Crawley,       from  many  as  four  or  even  six  parasites.    The  doubled  bodies 

Doflem,    Cir.  No.         i  •  •     n       i  i  i    i    j 

194,  Bu.  An.  ind.  enlarge,  assummg  a  spmdle-shaped  and  later  a  pear- 
u.  s.  Dept.  Agr.)  shaped  appearance.  Finally,  as  a  result  of  this  invasion, 
the  corpuscles  break  down,  and  the  parasites  become 
free  bodies  in  the  plasma.  That  a  multiplicative  stage  occurs  within 
the  bovine  host  is  evidenced  from  the  fact  that  inoculation  of  sus- 
ceptible cattle  with  a  small  quantity  of  virulent  blood  will  produce  the 
disease  with  the  development  of  myriads  of  the  parasites  in  the  blood  of 
the  inoculated  animals. 

Occurrence. — Numerous  attempts  have  been  made  to  produce  Texas 
fever  in  other  species  of  animals  by  inoculating  them  with  infected  blood 
from  cattle.  That  all  of  these  experiments  have  proved  negative  in- 
dicates that  the  disease  is  one  purely  bovine.  All  bovine  animals  that 
have  never  been  exposed  are  susceptible,  and  in  all  cases  natural  in- 
fection with  the  protozoan  causing  the  disease  is  due  to  puncture  by 
the  cattle  tick. 

The  disease  exists  in  European  and  Asiatic  countries,  Africa,  Australia, 
and  the  Philippine  Islands.  It  was  probably  introduced  into  the  United 
States  by  cattle  brought  over  by  the  early  Spanish  settlers.  The  terms 
"  Texas  fever  "  and  "  southern  cattle  fever  "  are  misleading  to  some  in 
giving  the  impression  that  the  disease  is  confined  to  the  Southern  States. 
Southern  cattle  carrying  the  infecting  organism  in  their  blood,  though 
themselves  possessing  degrees  of  immunity  to  Texas  fever,  disseminate 
it  through  ticks  from  their  bodies  among  cattle  in  the  North  or  among 
those  of  the  South  which  are  susceptible  to  the  disease  in  a  virulent 
form. 

Exposure  and  Development. — The  period  from  exposure  to  tick  in- 
fested pastures  or  pens  to  the  appearance  of  the  disease  depends  upon 
the  time  which  elapses  from  the  dropping  of  the  female  ticks  from  the 
southern  cattle  to  the  hatching  of  the  larvae  from  their  eggs,  and  this 


THE  PROTOZOAN  SUBGROUPS  349 

will  be  influenced  by  climatic  conditions.  If  the  larval  ticks  are  already 
present  and  at  once  attach  to  the  exposed  animals  symptoms  of  the  fever 
may  develop  ten  to  twelve  days  later.  Where  the  susceptible  animals 
are  placed  upon  pastures,  in  pens,  or  other  places  immediately  after 
these  have  been  infected  with  ticks  from  southern  cattle,  a  period  must 
intervene  covering  egg-laying  and  hatching  of  the  larvae  before  the 
northern  animals  become  inoculated.  In  sununer  this  period  may  oc- 
cupy from  twenty  to  forty  days;  in  cooler  weather  it  takes  longer  for  the 
eggs  to  hatch,  and  under  such  conditions  sixty  daj'S  or  longer  may  be 
required  before  the  infective  generation  of  ticks  appears.  Thus,  de- 
pending upon  season  and  temperature,  the  disease  may  appear  in  twelve 
days  to  two  or  three  months  after  exposure  (see  life  histor>'  of  Texas 
fever  tick,  page  148). 

Symptoms. — Two  distinct  types  of  Texas  fever  are  presented, — an 
acute  fatal  and  a  chronic  form,  from  the  latter  of  which  the  animals 
usually  recover.  Whether  the  fatal  or  the  milder  type  appears  will  de- 
pend upon  season  and  the  susceptibilty  of  the  animals.  When  northern 
cattle  and  those  raised  in  tick-free  districts  in  the  South  are  attacked  in 
the  hot  weather  of  summer,  the  acute  form  occurs.  If  the  susceptible 
animals  are  affected  in  the  latter  part  of  autumn  the  milder  chronic  spn- 
ptoms  appear,  and  it  is  bj'  this  type  of  the  disease  that  partly  immune 
southern  cattle  are  affected  at  any  season,  the  fatal  form  rareh'  attack- 
ing these  animals. 

The  Acute  Type. — In  this  form  of  the  disease  the  onset  of  the  symp- 
toms is  rapid.  The  animal  is  depressed  and  stands  or  lies  down  apart 
from  the  held,  there  is  loss  of  appetite  and  rumination  ceases.  The  tem- 
perature rises  within  twenty-four  to  forty-eight  hours  to  107°  or  108°  F., 
the  fever  accompanied  by  increase  in  the  rate  of  pulse  and  respiration. 
During  the  early  stages  of  the  disease  there  is  constipation  which 
is  generally  followed  by  diarrhea.  The  hemoglobin  released  by  the 
disintegration  of  the  corpuscles  causes  a  blood-stained  urine  (hemoglobi- 
nurea),  from  which  symptom  is  derived  the  name  "red  water,"  some- 
times given  to  the  disease.  Cerebral  disturbances,  exhibited  by  stag- 
gering, disorders  of  vision,  or  delirium,  may  appear  in  some  cases.  A 
conclusive  diagnosis  may  be  made  upon  finding  the  parasites  within  the 
corpuscles  by  microscopic  examination  of  the  blood. 

A  fatal  termination  is  usually  reached  within  three  or  four  days.  If 
recovery  occurs,  it  is  much  prolonged,  due  to  the  time  required  for  the 
generation  of  new  corpuscular  elements  to  replace  those  destroyed. 

The  Chronic  Type.— The  difference  in  the  symptoms  of  the  chronic 
type  of  the  disease  from  those  of  the  acute  is  one  of  degree.  Further, 
there  is  a  seasonal  difference,  the  milder  chronic  form  usually  appearing 
in  the  late  fall  and  early  winter,  the  acute  in  the  hot  sununer  months. 
The  temperature  does  not  go  as  high,  remaining  at  about  103°  F.  and 


350  PARASITES  OF  THE  DOMESTIC  ANIIVIALS 

not  exceeding  105°  F.  The  anaemic  condition  is  indicated  by  the  paleness 
of  the  visible  mucosae,  and  the  extended  course  brings  about  great 
emaciation.  In  these  cases  hemoglobin  is  not  usually  passed  with  the 
urine,  hence  hemoglobinurea  or  ''red  water,"  typical  of  the  acute  form, 
is  absent. 

Death  rarely  occurs  in  this  type  of  the  disease,  though,  due  to  its 
prolonged  course  and  the  excessive  loss  of  flesh,  much  loss  is  sustained 
in  the  productive  valuation  of  the  animal. 

Prevention  and  Treatment. — Prevention  is  by  measures  dealing 
with  the  cattle  tick  Margaropus  annulatus,  which  is  the  specific  carrier 
and  transmitter  of  the  protozoan  causing  the  disease.  As  study  of  the 
life  histoiy  of  this  tick  has  shown  that  it  will  not  mature  except  upon  a 
bovine  or  equine  host,  it  follows  that  it  can  be  exterminated  from  in- 
fested pi-emises  by  keeping  cattle  and  horses  off  of  such  premises  until 
the  larval  ticks,  unable  to  find  a  host,  have  perished.  With  this  purpose 
in  view,  systems  of  pasture  rotation  have  been  devised  additional  to 
methods  directed  toward  the  destruction  of  ticks  on  the  cattle  (Ref. 
Margaropiis  annulatus,  p.  145). 

Medical  treatment  of  animals  sick  with  Texas  fever  has  not  proved 
satisfactory.  In  the  milder  type  of  cases  the  constipation  may  be  re- 
lieved somewhat  by  Epsom  salts.  Repeated  doses  of  digitalis  during 
the  excessive  anaemia  and  the  administration  of  tonics,  such  as  gentian 
and  nux  vomica,  during  the  stage  of  convalescence,  have  been  recom- 
mended as  beneficial.  The  recovering  animal  should  have  free  access 
to  pure  water  and  a  generous  supply  of  nutritious  food. 

Order  III.    Sarcosportdia 

Sporozoa  (p.  336). — The  Sarcosporidia  are  parasites  in  striated 
muscle  cells  of  vertebrates.  Sporulation  takes  place  during  the  develop- 
ment of  the  trophozoite  which  becomes  surrounded  by  a  protective 
envelope. 

These  muscle  parasites  are  found  in  man,  in  domestic  and  wild  birds, 
and  are  common  in  domestic  mammals.  The  muscles  more  commonly 
invaded  are  those  of  the  upper  part  of  the  esophagus,  larynx,  the  body 
wall,  the  diaphragm,  and  the  psoas  muscles. 

Development. — Within  the  muscle  fiber  the  parasite  first  appears  as 
a  minute  body  in  which  stage  it  is  known  as  Miescher's  tube.  As  the 
young  ti'ophozoite  develops  it  becomes  multinuclear  and  surrounded  by 
a  membrane,  while  groups  of  spores  form  in  the  center  of  the  proto- 
plasmic body.  With  the  continuation  of  the  spore  formation  the  cyst 
enlarges,  causing  such  distension  of  the  muscle  fiber  as  to  result  in  its 
rupture,  releasing  the  cyst  which  ultimately  bursts,  the  spores  thus 
becoming  scattered  to  infest  new  muscle  cells.     By  repetitions  of  this 


THE  PROTOZOAN  SUBGROUPS 


351 


auto-infective  process  the  entire  skeletal  musculature  may  become 
affected.  More  or  less  destruction  of  muscle  tissue  is  thus  brought 
about  which  necessarily  is  relatively  injurious  to  the  host;  furthermore, 
the  effect  is  contributed  to  by  the  extremely  toxic  nature  of  the  parasites 
themselves. 

Importance  of  Sarcosporidiosis  and  Mode  of  Infection. — Hosts  show- 
ing high  incidence  of  infection  with  Sarcosporidia  among  domestic 
animals  are  pigs,  sheep,  cattle,  and  horses,  the  infecting  species  in  each 
case  being  Sa7-cocys(is  miescheriana  occurring  in  pigs,  S.  tenella  in  sheep. 


Fk;.  172. — Various  foini.s  of  Sarcospoiiilia.  _'.  S:iii(h\  >tis  lilani-hanli.  Longidtudinal 
section  of  an  infected  muscle  with  yount;  iiidi\i(lual  (after  Ciawley,  from  Doflein,  from 
VanEeckc,  Cir.  No.  194,  Bu.  An.  Ind.,  U.  S.  Dept.  Agr.).  3.  Sarcocystis  tenella  in  a 
Purkinje  cell  of  the  heart  of  a  sheep  (after  Crawley,  from  Doflein,  from  Schneidemuhl, 
Cir.  No.  194,  Bu.  An.  Ind.,  U.  S.  Dept.  Agr.).  4.  Sarcocystis  tenella  in  the  wall  of  the 
esophagus  of  a  sheep  (after  Crawley,  from  Doflein,  from  Schneidemuhl,  Cir.  No.  194,  Bu. 
An.  Ind.,  U.  S.  Dept.  Agr.).  5.  Sarcocystis  muris  in  muscles  of  mouse  (after  Crawley, 
Cir.  No.  194,  Bu.  An.  Ind.,  U.  S.  Dept.  Agr.). 

S.  hianchardi  in  cattle,  and  S.  berirami  in  horses.  In  these  animals  the 
infection  has  been  considered  as  of  little  pathologic  importance;  the 
sarcosporidiosis  is  apparently  never  fatal,  and  it  is  rare  to  find  an  animal 
visibly  affected.  This  conclusion,  however,  may  be  modified  somewhat 
by  further  study  of  the  parasite,  warranted  b}'  its  prevalence,  toxicity, 
and  possibly  greater  pathologic  import  than  at  present  supposed. 
Up  to  the  present  time  little  has  been  brought  to  light  as  to  the  life  his- 


352  PARASITES  OF  THE  DOMESTIC  ANIMALS 

toiy  of  the  Sarcosporidia  or  as  to  the  mode  by  which  they  infect.  They 
are  known  to  be  fatal  to  mice,  and  it  has  been  found  that  when  mice  are 
fed  upon  the  flesh  of  other  mice  containing  Sarcosporidia  they  become 
infected.  Hence  the  conclusion  follows  that  natural  transmission  occurs 
in  these  animals  through  their  habit  of  nibbling  at  their  dead;  but  this 
method  of  transfer  can  hardly  be  considered  in  the  case  of  sheep,  cattle, 
and  horses,  and  the  mode  of  infection  in  these  animals  remains  a  prob- 
lem. 

In  an  article  upon  the  Sarcosporidia  encountered  in  Panama  (Journal 
of  Parasitology,  March,  1915),  Darling  suggests  that  these  muscle 
parasites  of  vertebrates  are  aberrant  forms  of  the  Neosporidia  of  in- 
vertebrates, and  points  to  the  facility  with  which  herbivora  may  in- 
g3st  Neosporidia  with  leaves  and  other  vegetation  bearing  infected 
invertebrates  and  their  droppings.  "Is  it  not  possible,"  Darling  writes, 
"that  Sarcosporidia  may  be  sidetracked  varieties  of  some  of  the  Neo- 
sporidia of  invertebrates  which  have  invaded  the  musculature  of  a 
hospitable  though  b}^  no  means  definitive  host  and  are  unable  to  con- 
tinue further  their  life  cycle  and  escape  from  a  compromising  and  aber- 
rant position?"  The  high  incidence  of  infection  among  sheep,  cattle, 
horses,  and  swine  is  evidence  favoring  this  explanation. 


GLOSSARY 

Aberrant.     In  botany  and  zoiilogy,  differing  in  some  of  its  characters  from  the  group 

in  which  it  is  placed. 
Acari.     Arthropods  of  the  order  Acarina;  mites  and  ticks. 
Acaricide.     A  medicinal  agent  used  to  destroy  acari. 
Agamous.     In  zoology,  having  no  distinguishable  se.xual  organs. 
Amorphous.     Without  definite  form;  shapeless. 
Ambulatory.     Formed  or  adapted  for  walking. 
Ametabolic.     Pertaining  to  insects  and  other  animals  which  do  not  undergo  a 

metamorphosis. 
Anorexia.     Loss  or  absence  of  appetite. 

Antenna.     A  segmented  process  on  the  head  of  insects,  myriapods,  and  crustaceans. 
Anthelmintic.     A  medicinal  agent  used  to  destroy  or  expel  worms  from  the  intestinal 

tract. 
Apodal.     Without  feet. 
Apterous.     Without  wings. 
Aquatic.     Growing  in  or  frequenting  water. 
Arboreal.     Attached  to  or  frequenting  trees. 
Arista.     A  tactile  filament  at  the  end  of  the  antenna  of  an  insect. 
Article.     A  segment  or  part  of  the  body  connected  by  a  joint  with  another  segment 

or  part. 
Asexual.     Having  no  sex. 

Basis  capituli.     Basal  portion  of  the  capitulum  or  head  of  a  tick. 
Biiid.     Cleft  or  divided  into  two  parts. 

Bisexual.     Having  the  organs  of  both  sexes  in  one  individual. 
Buccal.     Pertaining  to  the  cheeks  or  mouth  cavity. 
Budding.     A  method  of  reproduction  by  which  a  protuberance  from  the  parent 

organism  develops  into  a  new  organism. 
Bursa.     A  sac  or  sac-like  cavity. 
Capitulum.     The  head  of  a  tick. 

Caryozoic.     Pertaining  to  parasites  which  live  in  the  cell  nucleus. 
Catalepsy.     Suspension  of  sensibility  and  voluntary  motion. 
Caudal.     Pertaining  to  the  tail. 
Cephalic.     Pertaining  to  the  head. 

Cephalothorax.     The  fused  head  and  thorax  of  arachnids. 

Chelae.     Pincer-like  terminations  of  certain  of  the  limbs  of  crustaceans  and  arachnids. 
Chelate.     Terminated  by  chela?. 
Chitin.     The  horny  substance  forming  the  harder  part  of  the  integument  of  insects 

and  other  arthropods. 
Cilia.     Hair-like  processes,  as  of  a  cell,  capable  of  vibratory  movement. 
Coelom.     The  body-cavity,  as  distinguished  from  the  intestinal  cavity;  the  periaxial, 

perivisceral,  or  perienteric  space. 
Ccelozoic.     Pertaining  to  parasites  which  live  in  the  ccclomic  cavities  of  the  body. 


354  GLOSSARY 

Coxa.  The  hip  or  hip  joint.  In  insects  and  other  arthropods  the  first  segment  of 
the  leg  from  the  body,  articulating  with  the  second  segment  or  trochanter. 

Cystogenous.     Producing  or  bearing  cells. 

Cytozoic.     Pertaining  to  parasites  which  live  within  the  cell  cytoplasm. 

Dentate.     Having  a  toothed  margin  or  tooth-like  projections. 

Denticulate.     Having  very  small  tooth-like  projections. 

Dimorphism.     The  pi'operty  of  assuming  or  of  existing  under  two  distinct  forms. 

Dipterous.     Having  two  wings;  belonging  to  the  insect  order  Diptera. 

Dorsum.     The  dorsal  surface  or  back  of  an  animal. 

Ecdysis.     The  process  of  casting  the  skin;  molting. 

Elytra.     The  fore-wings  of  beetles,  serving  to  cover  the  hind  wings. 

Enterozoic.     Pertaining  to  parasites  which  live  in  the  lumen  of  the  digestive  tract. 

Epimeron.     One  of  the  side-pieces  in  the  segment  of  an  arthropod  animal. 

Facet.     A  smooth,  flat,  circumscribed  surface. 

Fauna.     The  aggregate  of  the  animals  of  a  given  region  or  geological  period. 

Femur.  The  thigh  bone.  The  third  segment  of  the  leg  of  an  insect,  articulating 
proximally  with  the  trochanter  and  distally  with  the  tibia. 

Filiform.     Thread-like. 

Fission.  Reproduction  by  division  of  the  body  into  two  parts,  each  of  wliich  be- 
comes a  complete  organism. 

Flagellum.     A  whip-like  appendage  or  process  of  a  cell. 

Flora.     The  aggregate  of  the  native  plants  of  a  given  region  or  period. 

Gamete.     A  sexual  cell  or  germ  cell. 

Gametocyte.  An  adult  parasite,  as  in  the  Plasmodium  of  malaria,  when  in  its 
reproductive  form. 

Granular.     Consisting  of  grains  or  granules. 

Gregarious.     Inclined  to  gather  together,  as  to  live  in  flocks  or  herds. 

Habitat.     The  natural  abode  of  an  animal  or  plant. 

Halteres.     The  rudimentary  hind  wings  of  Diptera;  balancers. 

Haustellum.     A  proboscis  adapted  to  take  food  by  suction,  as  in  many  insects. 

Hematozoic.     Pertaining  to  parasites  which  live  in  the  blood. 

Hemelytra.     The  partially  thickened  anterior  wings  of  certain  insects. 

Hermaphroditism.     The  union  of  the  two  sexes  in  the  same  individual. 

Hexacanth.     The  sLx-hooked  tapeworm  embryo;  the  onchosphere. 

Hexapod.     A  six-footed  animal;  a  true  insect. 

Hyaline.     A  glassy  or  transparent  substance  or  surface. 

Imago.     The  final  or  adult  stage  of  insects. 

Infundibuliform.     Having  the  form  of  a  funnel. 

Labium.     In  insects,  the  lower  lip,  formed  by  the  second  pair  of  maxillae. 

Labrum.     In  insects,  the  upper  lip. 

Lobe.     A  somewhat  rounded  projection  or  division  of  an  organ  or  part. 

Macrogamete.     The  large  female  gamete  or  germ  cell. 

Macrogametocyte.     The  female  gametocyte. 

Mandibles.     In  arthropods,  the  anterior  pair  of  mouth  parts  which  form  biting  jaws. 

Marine.     Living  in  the  sea. 

Maxillae.  In  arthropods,  paired  appendages  behind  the  mandibles,  usually  serving 
as  accessoiy  jaws. 

Merozoites.     Asexually  formed  spores  of  the  malaria  parasite. 


GLOSSARY  355 

Mesothorax.     The  middle  segment  of  the  thorax  of  an  insect. 

Metabolism.     The  processes  concerned  in  the  building  up  of  protoplasm  and  its 

destruction. 
Metamere.     One  of  a  series  of  segments  composing  the  body,  as  in  many  worms 

;iii(l  in  arthropods. 
Metamorphosis.     Change  of  form  or  structure,  as  in  the  larval,  pupal,  and  imago 

stages  of  an  insect's  development. 
Metaphyta.     Plants  consisting  of  many  cells;  all  plants  above  the  Protophyta. 
Metathorax.     The  posterior  segment  of  the  thorax  of  an  insect. 
Metazoa.     Animals  which,  in  an  embryonic  condition,  possess  at  least  two  distinct 

germinal  layers;  all  animals  above  the  Protozoa. 
Microgamete.     The  male  germ  cell  consisting  of  a  detached  flagelliform  process  of 

a  niirrogametocyte. 
Microgametocyte.     The  parent  male  cell. 

Micron.     One  thousandth  of  a  millimeter;  a  unit  of  microscopic  measure. 
Molting.     The  shedding  of  the  hair,  feathers,  or  outer  layer  of  the  skin,  which  are 

replaced  by  new  growth. 
Morphology.     The  science  of  the  outer  form  and  internal  structure  of  animals  and 

l)Iants. 
Myasis.     A  disease  caused  by  the  presence  of  the  larvte  of  flies  in  or  on  the  body. 
Myiasis.     Same  as  myasis. 
Myiosis.     Same  as  myasis. 

Ocellus.     A  small  simple  eye  of  many  invertebrates. 
Octopod.     Having  eight  feet,  as  in  adult  arachnids. 
Onchosphere.     The  tapeworm  embryo;  the  hexacanth. 
Ookinete.     Same  as  zygote. 
Oospore.     Same  as  zygote. 
Operculum.     A  lid-like  process  or  part. 
Ovum.     An  egg  cell  or  egg. 
Ovigerous.     Egg  bearing. 
Oviparous.     Producing  eggs  that  hatch  after  they  have  passed  from  the  body  of  the 

l)arent. 
Oviposition.     The  laying  of  eggs,  especially  applied  to  insects  and  arachnids. 
Ovipositor.     A  specialized  organ,  as  in  certain  insects,  for  depositing  eggs. 
Ovoviviparous.     Producing  eggs  that  have  a  well  developed  shell  or  covering,  as  in 

oviparous  animals,  but  which  incubate  within  the  body  of  the  parent. 
Ovulation.     The  formation  of  eggs  in  the  ovary;  the  discharge  of  the  egg  or  eggs 

from  the  ovary. 
Palpi.     Appendages,  usually  organs  of  touch  or  taste,  attached  to  the  mouth  parts 

of  insects  and  other  arthropods. 
Papilla.     A  small  nipple-like  or  pimple-like  projection. 
Parasiticide.     A  remedy  that  destroys  parasites. 
Parthenogenesis.     The  production  of  individuals  from  ova  without  fertilization  by 

tlic  male  element. 
Pedipalpi.     Leg-like  or  pincer-like  appendages  of  arachnids,  located  on  each  side  of 

the  mouth. 
Phylogenic.     Pertaining  to  the  ancestral  history  of  an  animal  or  plant. 
Phytozoon.     A  colony  of  animals  resembling  a  plant. 


356  GLOSSARY 

Plasmodium.     A  mass  of  protoplasm  formed  by  the  union  of  two  or  more  amebiform 

bodies  or  individuals. 
Plumose.     Feathery;  plume-like. 

Pollenose.     Bearing  a  powdery  or  pollen-like  substance. 
Predacious.     Living  bj'  prej-ing  on  other  animals. 
Prehensile.     Adapted  for  gi-asping. 
Proboscis.     The  tubular  process  of  the  head,  especially  of  insects  and  arachnids, 

adapted  for  sucking  or  piercing. 
Proglottid.     The  segment  of  a  tapeworm. 
Pro  thorax.     The  anterior  segment  of  the  thorax  of  an  insect. 
Protophyta.     The  division  of  unicellular  plants. 
Protozoa.     The  phylum  consisting  of  the  unicellular  animals. 
Pruritus.     An  intense  degree  of  itching. 
Pseudopodia.     Processes  of  the  protoplasm  of  a  cell  which  may  be  protruded  or 

retracted,  as  for  locomotion  or  for  taking  food. 
Pubescent.     Arrived  at  puberty,  or  the  earliest  age  at  which  the  reproductive  func- 
tion can  be  performed. 
Puparium.     The  case  in  which  an  insect  is  enclosed  between  its  larval  stage  and 

the  state  of  full  development  or  imago. 
Pupiparous.     Pertaining  to  insects  in  which  the  young  are  born  ready  to  become 

pupse,  as  in  the  sheep  tick. 
Quiescent.     At  rest. 

Rostellum.     A  small  beak  or  hook-like  process. 
Rostrum.     A  beak-like  process  or  appendage. 

Saproph5rte.     Any  vegetable  organism  living  on  dead  or  decaying  organic  matter. 
Schizogenesis.     Reproduction  by  fission. 
Schizogony.     Same  as  schizogenesis. 
Schizont.     A  malaria  parasite  of  the  asexual  generation. 
Scolex.     The  head  of  a  tapeworm,  either  in  the  larval  or  adult  stage. 
Scutum.     The  dorsal  shield  or  plate,  present  in  certain  ticks. 
Serrate.     Notched  or  toothed  on  the  edge. 
Somatic.     Pertaining  to  the  body  as  a  whole. 
Somite.     One  of  the  longitudinal  segments  into  which  the  body  of  annelid  worms, 

arthropods,  and  vertebrates  is  divided. 
Spiracle.     A  breathing  orifice,  as  in  the  tracheal  openings  of  insects. 
Spore.     A  germ  or  seed  of  one  of  the  lower  animals  or  plants. 
Sporocyst.     A  case  or  cyst  containing  many  spores. 
Sporogenesis.     Reproduction  by  means  of  spores. 
Sporogony.     Same  as  sporogenesis. 
Sporozoite.     One  of  the  young  active  spores  of  a  sporozoan  produced  by  division  of 

the  passive  spores  contained  in  the  sporocyst. 
Sporulation.     Spore  formation. 
Stigmata.     Small  spots  or  marks;  usually  applied  to  the  respiratory  openings  of 

insects;  spii-acles. 
Strobila.     An  adult  tapeworm. 
Suctorial.     Adapted  for  sucking. 
Tarsus.     In  insects,  the  small  segments  forming  the  distal  termination  of  the  leg 

and  articulating  with  the  tibia. 


GLOSSARY  357 

Tergum.     In  zoology,  the  back. 

Terrestrial.     Of  or  inhabiting  the  land  or  ground  in  distinction  from  trees,  water,  etc. 

Tibia.     In  insects,  the  fourth  segment  of  the  leg,  articulating  proximally  with  the 

femur  and  distally  with  the  tarsi. 
Tracheae.     The  air-conveying  tubules  forming  the  respiratory  system  of  insects  and 

other  arthropods. 
Trenchant.     Sharp;  cutting. 
Trochanter.     In  insects,  the  second  segment  of  the  leg,  ai-ticulating  proximally  with 

the  coxa  and  distally  with  the  femur. 
Vacuole.     A  cavity  or  vesicle  in  cell  protoplasm. 
Vermicide.     A  substance  which  kills  worms;  a  drug  to  kill  parasitic  worms  of  the 

intestines. 
Vermifuge.     A  medicine  that  expels  worms  from  the  bodies  of  animals. 
Verminous.     Infested  with  worms,  or  caused  by  worms,  as  verminous  diseases. 
Viviparous.     Producing  living  young  by  true  birth,  as  in  mammals,  and  not  by 

hatching  from  eggs,  as  in  oviparous  and  ovoviviparous  animals;  often  applied 

to  the  bringing  forth  of  young  which  have  been  hatched  from  eggs  within  the 

body  of  the  parent. 
Zoophyte.     Same  as  phytozoa. 
Zygote.     The  encysted  stage  of  certain  sporozoans  after  fertilization  by  a  sperm 

cell  and  before  division  into  spores. 


INDEX 


Acanthia  lectularia,  90 
Acanthocephala,  217,  224,  300 
Acariasis,  96 
Acarina,  94 

parasitism  of,  95 
Ades  calopus,  29 
Agriostomum,  280 
Amblyonima,  142 

americanuni,  145 
Ameba,312,324 

budding,  313 

ectoplasm,  312 

encystation,  313 

endoplasm,  312 

fission,  313 

method  of  feeding,  313,  324 

morphologic  characteristics,  312 

motility,  312,  324 

nucleus,  313 

pseudopodia,  312,  324 

reproduction,  313,  324 

respiration,  313 

streaming  of  cytoplasm,  312,  313, 
324 

vacuoles,  312,  313 
Ameba  meleagridis,  325 
Amebic  dj'sentery,  326 

in  man,  326 
American  dog  tick,  143 
Amphistomidse,  157,  167 
Amphistomum  cerv'i,  167 
Ankylostoma,  280 

canina,  291 

duodenale,  292 
Ankjdostomeae,  280 
Ankylostomiasis,  291 
Ankylostomimi  stenocephalum,  292 


Annelida,  224,  307 
Anopheles,  26,  320 

maculipennis,  26 

punctipemiis,  2S 

c^uadrimaculatus,  26 
Anoplocephala  mamillana,  175 

perfoliata,  174 

plicata,  175 
Anthelmintics,  use  and  action 

of,  221 
Apterous  insects,  IS 
Arachnida,  94 

classification  of,  96 
Arduenna,  228 

strongylina,  251 
Arduenninae,  228 
Argasidae,  97,  139 
Argas  americanus,  139,  327 

miniatus,  139,  327 
Arthropoda,  The,  13 

circulatory  system,  14 

digestive  system,  14 

excretory  organs.  14 

musculature,  14 

nervous  system,  14 

reproduction,  15 

res]Dirator}'  system,  14 

sense  organs,  15 

structure  in  general,  13 
Arthropoda  as  transmitters  of  infec- 
tious diseases,  313,  315 
Arthropoda,  parasitic  subgroups  of  15 
Ascariasis,  229,  231 

importance  of  treatment,  233 

location  of  wonns,  229,  232 

occurrence,  231 

pathogenic  influences,  232 


360 


INDEX 


Ascariasis  of  the  cat,  237 

occurrence,  239 

treatment,  239 
Ascariasis  of  the  dog,  237 

occurrence,  238 

post-mortem  appearance,  239 

treatment,  239    ■ 
Ascariasis  of  the  hog,  239 

effect,  240 

treatment,  241 
Ascariasis  of  the  horse,  l33 

control,  234 

etiology,  234 

occurrence,  233 

sj-mptoms,  233 

treatment,  234 
Ascariasis  of  the  ox,  241 
Ascariasis  of  the  sheep,  241 
Ascaridffi,  222,  229 

parasitism  of,  229,  231 
Ascaris,  225,  229 

equi,  233 

equorum,  233 

lumbricoides,  229,  239 

marginata,  237 

megalocephala,  233 

mystax,  237,  239 

ovis,  229,  239 

suis,  229,  239 

suum,  229,  239 

vitulorum,  241 
Ascaroidea,  225 

Auricular  mange  of  the  cat,  118 
Auricular  scabies  of  the  rabbit,  118 


B 

Bacillary  white  diarrhea  of  chicks,  345 
Bacterium  pullorum,  345 
Bathmostomum,  281 
Bedbug,  The  8,  90 

as  a  pest  of  poultry,  90 

control,  92 

effect  of  bite,  90 


habits,  90 

reproduction  and  development,  90 
Beef  measles,  174,  194,  195 

degeneration  of  cyst,  198 

development,  197 

federal  regulations  in  regard  to,  199 

influence  of  temperature,  198 

location  and  appearance,  197 

method  of  infection,  197 

occurrence,  196 

vitality  of  larvae,  198 
Beef  and  pork  tapeworm,  methods  of 

differentiation,  200 
Beef  tapeworm,  170,  195 
Belascaris  marginata,  237 

mystax,  237,  239 

cati,  237,  239 
Bilharzia  bovis,  168 

crassa,  168 
Bilharziosis,  168 
Black  gnat,  31 
Blackhead  of  turkeys,  325 
Black  horse  fly,  35 

as  a  transmitter  of  disease,  36 

effect,  35 

life  history,  35 

protection  from,  36 
Blood  fluke,  168 
Blow  fly,  50,  52 

effect,  53 

reproduction  and  development,  52 
Bluebottle  fly,  52 
Body  louse,  79 
Body  mange  of  poultry,  132 
Boophilus,  142 

annulatus,  144,  145,  314,  347 
bovis,  144,  145,  314,  347 
decoloratus,  316 
Bot  flies,  53 
Bot,  horse,  5,  53,  57 
Bothriocephalus  latus,  185 
Brachiopoda,  155 

Bronchial  and  pulmonary  strongylosis 
of  cattle,  259 


INDEX 


361 


control,  264 

course,  260 

development,  263 

etiology,  263 

post-mortem  appearance,  262 

prognosis,  260 

symptoms,  259 

sjTnptoms,  duration  of,  260 

treatment,  265 
Bronchial  and  pulmonary  strongylosis 
of  the  horse,  261 

occurrence,  261 

symptoms,  261 
Bronchial  and  pulmonary  strongylosis 
of  the  pig,  260 

occurrence,  260 

symptoms,  260 
Bronchial  and  pulmonary  strongylosis, 
post-mortem  appearance,  262 

control,  264 

development,  263 

etiology,  263 

treatment,  265 
Bronchial  and  pulmonary  strongylosis 
of  the  sheep  and  goat,  256 

control,  264 

course,  259 

development,  263 

etiology,  263 

post-mortem  appearance,  262 

prognosis,  259 

symptoms,  258 

treatment,  265 
Buffalo  gnat,  31,  32 

control,  33 

effect,  33 

life  history,  32 

occurrence,  32 

protection  from,  33 

treatment,  34 
Brazilian  septicemia  of  fowl,  327 
Bruce,  investigations  of,  45,  315,  330 
Bryozoa,  155 
Bunostomeae,  281 


Bunostomum  trigonocephalum,  293 
phlebotomum,  293 


Calliphora  vomitoria,  52 
Cardiac  filariasis  of  the  dog,  248 
Cardio-pulmonary  strongylosis  of  the 
dog,  261 

post-mortem  appearance,  263 

symptoms,  262 
Castor-bean  tick,  143  . 
Cattle  tick,  144,  145,  314,  347 
Cestoda,  159,  169 
Chabertia  ovina,  287 
Chiggers,  96,  99 
Chloroform    as    ti-eatment    for    lung 

woi-ms,  266 
Choanotainia  infundibuliformis,  189 
Chorioptes,  103 

parasitism,  103 

species,  103 
Chorioptes  communis,  103 

var,  bovis,  113 

var.  equi,  108 

var.  ovis,  112 
Chorioptic  scabies  of  cattle,  113 

course,  113 

location,  113 

treatment,  120,  130 
Chorioptic  scabies  of  the  horse,  108 

course,  108 

diagnosis,  109 

lesions,  109 

prognosis,  109 

symptoms,  108 

transmission,  109 

treatment,  120,  129 
Chorioptic  scabies  of  the  sheep,  112 

course,  112 

prognosis,  112 

symptoms,  112 

transmission,  112 
Chrysomyia  macellaria,  50 


INDEX 


Cimex  lectularius,  90 

Cimicidffi,  22,  90 

Citto  taenia  denticulata,  185 

Classification  of  the  Arachnida,  96 

Classification  of  the  phylum  Ccelhel- 

minthes,  222 
Classification  of  Insects,  20 
Classification  of   the  phylum  Platy- 

helminthes,  157 
Classification  of  the  plyhun  Protozoa, 

322 
Cnemidocoptes,  103,  132 

species  of,  103,  132 
Cnemidocoptes  gallinse,  103,  133 

mutans,  103,  132 
Coccidia,  322,  323,  337 

infection,  337 

life  cycle,  322,  337 

parasitism,  337 

pathogenicitj^,  337 

reproduction,  337 
Coccidial  enteritis  of  chicks,  345 

control,  346 

diagnosis,  345 

differentiation  from  bacillary  white 
diarrhea,  345 

infection,  346 

post-mortem  appearance,  345 

symptoms,  345 
Coccidiosis  of  the  dog,  342 

investigations  bj^  Hall  and  Wigdor, 
342 
Coccidiosis  of  cattle,  343 

of  chicks,  345 

of  the  dog,  345 

of  man,  342 

of  the  rabbit,  342 
Coccidium  cuniculi,  342 

oviforme,  342 

tenellum,  345 

zurni,  343 
Cochliomyia  macellaria,  50 
Ccelhelminthes,  216 

classification  of,  156,  216,  222 


Coelom,  216 

Coenurosis,  204 

Coenurus,  173, 194,  204, 205 

Colic,  thrombo-embolic,  288,  290 

Commensalism,  2,  7 

example  of,  2,  7 
Compsomyia  macellaria,  50 
Connective    tissue  mite   of   poultry, 

134 
Cooperia  curticei,  268 

oncophora,  275 
Cryptobia,  329 
Cryptocystis,  178,  195 
Ctenocephalus  cards,  65,  79 

felis,  65 
Culex  and  Anopheles,  differentiation, 

28 
Culex  pungens,  26,  28 
Culicidse,  20,  24 
Cylicostomese,  281 
Cylicostomum,  281 
Cysticercoid,  173,  178,  195 
Cysticercosis,  174,  195 
Cysticercus,  173,  174,  194,  195 

bovis,  174,  195,  197 

cellulosEe,  174,  195,  199,  202 

ovis,  203 

tenuicollis,  174,  179,  195,  203 

trichodectes,  79, 178,  183 
Cytoleichidffi,  134 
Cytoleichus  nudus,  134 

D 

Davainea  cesticillus,  190,  191 

echinobothrida,  191 

proglottina,  189 

tetragona,  190,  191 
Degeneration,  parasitic,  3,  4 
Demodecidae,  96,  97,  103 
Demodectic  mange,  96,  104 

of  the  dog,  116 

of  the  hog,  115 

of  the  sheeji,  112 


INDEX 


363 


Demodex  foUiculorimi,  10-i 

var.  canis,  104,  116 

var.  ovis,  104,  112 

var.  snis,  104,  115 
Depluming  mange  of  poultry,  133 
Deplimaing  mite,  101,  133 
Dermacentor,  142 

electus,  143 

occidentalis,  143 

reticulatus,  143 

variabilis,  143 
Dibothriocephalus  latus,  185 
Dibothrium  latum,  185 
Dicrocoelium  lanceatum,  160,  163 
Dictyocaulus  arnfieldi,  261 

filaria,  221,  256 

viviparous,  259 
DioctophjTiie  renale,  296 

\'isceralis,  296 
Diphyllobothriasis,  185 

occurrence,  186 
Diphyllobothriidae,  160,  185 
Diphyllobothrium  latum,  185 
Diplospora  bigemina,  342 
Dipping  vats,  126 
Dips,  48,  120,  125 
Diptera,  18,  20 

parasitic  families  of,  23 

parasitism  of,  23 
Dipterous  insects,  18,  23 
Dipylidium  caninum,  68,  79,  178,  181, 

^183 
Dirofilaria  inmiitis,  221,  248 
Dispharagus  hamulosus,  254 

nasutus,  254 

spiralis,  254 
Distomese,  156,  157 
Distomiasis,  157,  163,  165 

of  cattle,  166 

of  the  sheep,  165 
Distomvun  americanum,  160 

hepaticum,  160 

lanceolatum,  160 

magnvun,  160 


Dochmiasis,  291,  292 
Doclmiius  cernuus,  293 

radiatus,  293 

stenocephalus,  292 

trigonocephalus,  291 
Docophorus  cygni,  86 

icterodes,  84 
Dourine,  333 

control,  336 

federal  control  of  outbreaks,  333 

infection,  333,  334 

stages  in,  334 

sjTiiptoms,  334 
Drepanidotsenia  infundibulifomiis,  189 
D3^sentery  of  cattle,  343 


Earthwonn,  216 
Ecdysis,  13 

Echinococcosis,  183,  210 
Echinococcus,  173,  181,  183,  194,  210 

alveolaris,  212 

granulosus,  181,  183,  184,  194,  210 

multilocularis,  210,  212 

pohiiiorphus,  181,  183,  210 
Echinorh^^lcllus  gigas,  306 
Ectozoa,  9 
Eimeria  avimn,  345 

stiedse,  342 
El  dourine,  333 
Endoparasites,  9 
Entameba,  326 

coli,  326 

histolytica,  326 
Entero-hepatitis  of  turkeys,  325 
Entozoa,  9 
Erratic  parasites,  8 
Esophageal  and  gastric  filariasis  of  the 
dog,  250 

course,  251 

development,  251 

occurrence,  250 

pathogenesis,  250 


364 


INDEX 


symptoms,  251 

treatment,  251 
Esophageal  filariasis  of  cattle,  246 

of  the  dog,  250 

of  the  sheep,  246 

of  the  horse,  247 
European  dog  tick,  143 
EustrongyUdffi,  224,  296 
Eustrongylosis,  296 

occurrence,  296 

symptoms,  297 

treatment,  298 
Eustrongylus  gigas,  296 

visceralis,  296 
Exoparasites,  9 


Fasciola  americana,  160,  163 

hepatica,  5,  160 

lanceolata,  160,  163 

magna,  160, 163 
Fasciola  hepatica,  life  history  of,  5, 160 
Fasciola  lanceolata,  life  history  of,  163 
Fasciola  magna,  life  history  of,  163 
FascioHasis,  157, 163, 165 
Fascioliasis  of  cattle,  166 

control,  167 

symptoms,  166 

treatment,  168 
Fascioliasis  of  the  sheep,  165 

control,  167 

course,  165 

prognosis,  166 

symptoms,  165 

treatment,  168 
FascioHdae,  157, 160 
Filaria,  227 

bancrofti,  249 

cervina,  248 

equina,  244 

immitis,  248 

labiato-papillosa,  248 

sanguinis  hominis,  249 

sanguinolenta,  250 


Filariae  of  cattle,  246 

of  the  dog,  248 

of  the  hog,  251 

of  the  horse,  244 

of  poultry,  254 

of  the  sheep,  246 
Filariasis  of  cattle,  246 

effect,  247,  248 

occurrence,  247,  248 
Filariasis  of  the  deer,  248 
Filariasis  of  the  dog,  248 

diagnosis,  249,  251 

occurrence,  248,  250 

pathogenesis,  249,  250 

theories  as  to  infection,  249 

treatment,  250,  251 
Filariasis  of  the  hog,  247,  251 

control,  253 

occurrence,  252 

treatment,  254 
Filariasis  of  the  horse,  244 

effect,  245,  246 

occurrence,  244,  245,  246 

treatment,  246 
Filariasis  of  poultry,  254 
Filariasis  of  the  sheep,  246 

effect,  247 

occurrence,  247 
Filariidse,  222,  244 

parasitism  of,  244 
Filarioidea,  227 
Fixed  parasites,  8 
Flagellata,  322,  326 
Fleas,  65 

as  carriers  of  disease,  66 

control,  68 

habits,  66 

household  infestation,  69 

reproduction  and  development, 
65,66 

species,  differential  characters  of,  65 

treatment,  68 

usual  hosts,  66 

vitality,  68 


INDEX 


365 


Flesh  flies,  50,  52 

protection  from,  52 

reproduction  and  development,  52 
Flies,  11,23,35 
Fluke,  liver,  5,  156,  160,  163 
Fly,  house,  11,37,  189 
Follicular  mange  of  the  dog,  116 

course,  116 

symptoms,  116 

transmission,  117 

treatment,  130 
Follicular  mange  of  the  hog,  115 

occurrence,  115 

treatment,  130 
Follicular  mange  mite,  103 
Follicular  mange  of  the  sheep,  112 

location,  112 

prevalence,  112 
Forked  worm  of  fowl,  293 
Fowl  septicemia,  327,  345 
Fowl  tick,  139 

control,  140 

development,  140 

effect,  140 

habits,  140 

occurrence,  140 
Fumigation  treatment  in  venninous 
bronchitis,  and  pneumonia,  265 


Oaigeria,  281 
Gamasidse,  96,  98 
Gamasid  mifes,  96,  98 
Gastric  filariasis  of  the  dog,  250 
Gastric  filariasis  of  the  horse,  245,  246 
Gastric  and  intestinal  filariasis  of  the 

hog,  251,  252 
Gastro-intestinal  strongylosis  of  cattle, 
272 

control,  276 

development,  276 

etiology,  276 

occurrence,  275 


pasture  rotation,  277 

post-mortem  appearance,  275 

symptoms,  275 

treatment,  277 
Gastro-intestinal   strongylosis  of  the 

goat,  268 
Gastro-intestinal  strongylosis  of   the 
sheep,  268 

control,  276 

development,  276 

etiology,  276 

occurrence,  271 

pasture  rotation,  277 

pathogenesis,  272 

post-mortem  ap])earance,  275 

sjin])toms,  272 

treatment,  277 
Gastrophilus  equi,  5,  53 

hemorrhoidalis,  57 

intestinalis,  5,  53 
Gid  of  cattle,  205,  209 
Gid  of  the  sheep,  204 

the  coenurus,  205 

control,  209 

development,  206 

occurrence,  205 

post-mortem  appearance,  207 

symptoms,  208 

treatment,  209 
Gigantorhynchus  hirudinaceus,  306 
Glossary,  353 
Glossina,  44,  314 

longipalpis,  44,  46 

morsitans,  44,  46,  330 

palpalis,  44,  46 
Gnat,  buffalo,  31,  32 
Gnathobdellidc^,  224,  308 
Gnats,  31 
Gongylonema,  227 

scutata,  246 
Gongylonemina',  227 
Goniocotes  abdominalis,  82 

compar,  86 

gallinre,  82 


366 


INDEX 


gigas,  82 

hologaster,  82 
Goniodes  damicornis,  86 

stylifer,  S4 
Grammoceplialus,  281 
Green-head  fly,  36 
Gyalocephalus,  281 

H 

Habronema  megastoma,  245 

microstoma,  246 
Haemaphysalis,  142 
Hcematobia  serrata,  41 
Hsematopiims  asini,  73 

eurj-stermis,  74 

macroeephalus,  73 

suis,  77 

urius,  77 
Hsemonchus  coutortus,  268 
Hsemopis  sanguisuga,  308 
Harvest  mites,  99 

effect,  100 

habits,  100 

protection  from,  100 

treatment,  100 
Heel  fly,  57 
Hehninthes,  9 
Helotism,  7 
Hematic  filariasis  of  the  dog,  248 

diagnosis,  249 

occurrence,  248 

pathogenesis,  249 

theories  as  to  infection,  249 

treatment,  250 
Hematic  filariasis  of  man,  249 
Hemiptera,  22,  89 
Hemosporidia,  323,  347 

dift'erence  in  m:de  of  infection  from 
Coccidia,  337,  347 

relationship  to  other  groups,  336, 
347 

relative  pathologic  importance,  347 
Hepatic  coccidiosis  of  rabbits,  342 


Herpetomads,  316 

experiments  -with,  316 
Herpetomonas  donovani,  316 
Heterakiasis  of  poultr}-,  242 

sj-mptoms,  243 

treatment,  243 
Heterakidse,  222,  242 
Heterakinse,  226 
Heterakis,  226 

inflexa,  242 

papillosa,  242 

perspicillum,  242 

vesicularis,  242 
Heteroxenous  parasites,[S 
Hippoboscidse,  21,  47 
Hirudinea,  224,  307 
Hirudo  medicinahs,  309 
Hook  wonn,  291,  292 
Horn  fly,  41 

control,  43 

effect,  42 

habits,  41 

life  histon,',  41 

occurrences,  41 

protection  from,  43 
Horse  bot  flies,  5,  53 

effect  of  bots,  55 

habits,  53 

life  historj',  54 

treatment,  56 
Horse  leech,  308 

efi'ect,  309 

mode  of  infestation,  309 

occurrence,  309 

treatment,  309 
House  flj',  11,  37,  189 

as  a  transmitter  of  infectious  dis- 
eases, 11,  38, 189 

control,  38 

habits,  38 

life  historj',  37 

longevity,  37 

protection  from,  38 
Hvalomma,  142 


INDEX 


367 


Hydatid  disease,  173,  ISl,  1S3, 194, 210 

control,  214 

development,  212 

the  echinococcus,  210 

longe\'ity  of  cyst,  213 

occurrence,  210 

post-mortem  appearance,  213 

sj-mptoms,  214 
Hjinenolepis  carioca,  190,  191 
HjTnenoptera,  18 
Hypoderma  bo-\ds,  58 

lineata,  57 


Imago,  The,  19 
Incidental  parasites,  8 
Infectious  entero-hepatitis  of  turkeys, 
325 

control,  326 

course,  325 

infection,  325 

post-mortem  appearance,  325 

symptoms,  325 

treatment,  326 
Insecta,  15 

classification  of,  20 
Insects,  15 

development,  18 

duration  of  life,  19 

growth,  19 

lar\'2e,  18 

metamorphosis,  18 

mouth  parts,  16 

parasitic  subgroups,  20 

reproduction,  18 

structure,  15 
Internal  parasites,  155 
Intestinal  strongj'losis  of  the  cat,  291 

of  cattle,  272,  285 

of  the  dog,  291 

of  the  goat,  268,  281,  287 

of  the  hog,  287 

of  the  horse,  288 

of  the  sheep,  268,  281,  287 


Intratracheal  injections,  265 
Introduction,  1 
Isospora  bigemina,  342 
Itch  mites,  101 
Ixodes,  142 

hexagonus,  143 

ricinus,  143 
Ixodidjp,  96, 97, 136,  141 
Ixodoidea,  96,  97,  136,  139 

K 

Kala-azar,  316 

Kerosene  emulsions,  48 

Kerosene    in    mosquito    control,    25, 

31 
Kidney  womi  of  the  dog,  296 
Kidney  worm  of  the  hog,  295 


Laminosioptes  cysticola,  134 
Lan'se,  dipterous,  50 
Lar\'3e,  insect,  18 
Leeches,  216,  307 
Leg  mange  of  poultrj-,  132 
Leishmania  donovani,  316 
Leptus  autumnalis,  100 
Lice,  70 

biting,  71 

sucking,  70 
Lice  of  poultry,  82 

control,  88 

occurrence,  82 

treatment,  88 
Life,  degeneracj'  in  mode  of,  1 
Life  history  of  beef  tapeworm,  tabular 

re\iew,  172 
Life  histories  of  dog  tick  and  Texas 

fever  tick  compared,  151 
Life  historj'  of  Echinococcus  granu- 
losus, tabular  review,  213 
Life  historj'  of  gid  tapeworm,  tabular 
review,  207 


368 


INDEX 


Life  history  of  horse  botfly,  tabular 

review,  55 
Life   history   of   liver   fluke,    tabular 

review,  163 
Life  history  of  sheep  botfly,  tabular 

review,  63 
Life    history  of   Trichinella    spiralis, 

tabular  review,  303 
Lime  and  sulphur  dips,  122,  125 

method  of  preparing,  125 
Linguatula  rhinaria,  94,  153 
Lin;uatulida,  153 
Linguatulidse,  97 
Linognathus  pedalis,  76 

piliferus,  78 

stenopsis,  77 

vituli,  74 
Liotheidse,  22,  71 
Lipeurus  anatis,  84 

baculus,  86 

caponis,  83 

columbae,  86 

heterographus,  83 

meleagridis,  84 

polytrapezius,  84 

squalidus,  84 

variabilis,  83 
Lissoflagellata,  328 
Liver  flukes,  5,  156,  160 

infection,  160,  164 

life  history,  5,  160 

losses  from,  162 

migrations  and  pathogenesis,  164 

prevalence,  162 

prevalence  in  United  States,  164 
Lobosa,  322,  324 
Lone  star  tick,  145 
Lousiness,  71 
Lung  worms,  256 

control,  264   ' 

development,  256,  263 

method    of    infection    with,    256, 
263 
Lyperosia  irritans,  41 


M 


Maladie  du  coit,  333 
Malaria,  26,  318 
Malaria,  latent,  322 
Malaria  organisms,  the  asexual  cvcle, 
318,  319 
the  gametocytes,  319 
hberation  of  the  merozoites,  319 
the  macrogametocyte,  319 
the  merozoites,  319 
the  microgametes,  319 
the  microgametocyte,  319 
relation  of  liberation  of  merozoites 

to  chill,  319 
repeating  of  cycle,  319 
the  schizont,  319 
the  signet  ring  stage,  319 
the  sporozoites,  319,  320 
Malaria  organisms,  life  history,  318 
Malaria  organisms,   the   parthenoge- 

netic  phase  of,  322 
Malaria  organisms,  the  sexual  cycle, 
320 
fertilization   of    the   macrogamete, 

320 
fomiation  of  cyst,  320 
formation  of  macrogamete,  320 
formation    of    the    microgametes, 

320 
fonnation  of  the  sporoblasts,  320 
formation  of  the  sporozoites,  320 
liberation  pf  the  sporozites,  320 
the  microgametoblast,  320 
migration  of  ookinete,  320 
the  ookinete  or  zygote,  320 
passage  of  sporozoites  to  salivary 

glands  of  mosquito,  320 
relationship  of  anopheline  mosquito 
to,  26,  313,  319,  320 
Mai  de  caderas,  332 
infection,  333 
occurrence,  332 
symptoms,  332 


INDEX 


Mallophaga,  21,  71 
Mange,  96,  101,  102,  103,  104,  112, 
113,  114,  115,  116,  117,  118 

cnemidocoptic,  132 

follicular,  102,  112,  115,  116 

notoedric,  118 

sarcoptic,  102, 104, 112, 114, 121 
Mange    of    the    body     of     poultry, 
133 

course,  133 

symptoms,  133 

treatment,  133 
Mange  of  the  cat,  117 

course,  118 

diagnosis,  118 

treatment,  120,  123 
Mange  of  cattle,  114 

treatment,  120,  124 
Mange  of  the  dog,  115,  116 

course,  115,  116 

lesions,  115, 116 

symptoms,  115,  116 

transmission,  115,  117 

treatment,  120,  123,  130 
Mange  of  the  goat,  1 13 

treatment,  120,  124 
Mange  of  the  hog,  114,  115 

sjTnptoms,  114,  115 

transmissions,  114 

treatment,  120,  122,  130 
Mange  of  the  horse,  104 

control,  122 

development,  105 

diagnosis,  105 

lesions,  105 

prognosis,  107 

symptoms,  104 

transmission,  107 

treatment,  120,  121 
Mange  of  the  legs  of  poultry,  132 

course,  132 

symptoms,  132 

treatment,  132 
Mange  mites,  96,  103,  132,  134 


Mange  of  poultry,  132,  134 
Mange  of  tlie  rabbit,  118 

treatment,  120,  124 
Mange  and  scab  mites,  96,  101,  102, 
103,  117,  132,  134 

development,  101,  103 

reproduction,  101,  103 
Mange  of  the  sheep,  112 

treatment,  120,  124 
Margaropus,  142,  145 

annulatus,  144,  145,  314,  347 
Mastigophora,  322,  326 
Measles,  174,  194,  195 

ofman,  174,  194,  195 

of  the  ox,  174,  195 

of  the  pig,  174,  195 

of  the  sheep,  174,  195 
Medicinal  leech,  309 
Melophagus  ovinus,  4,  47,  76 
Menopon  biseriatum,  83 

pallidum,  83 
Menopum  biseriatum,  83 

pallidum,  83 

trigonocephalum,  83 
Metamorphosis,  insect,  19 

complete,  19 

incomjjlete,  19 
Metastrongylidae,  227 
Metastrongylina>,  223,  256 

life  history,  256,  263 
Metastrongylus,  227 
Metazoa,  311 
Miescher's  tube,  350 
Mites,  94 
MoUuscoidea,  155 
Molting,  13 
Moniezia  alba,  176 

denticulata,  185 

expansa,  176 

planissima,  176 
Monoxenous  parasites,  8 
Mosquitoes,  11,  24 

breeding  habits,  24 

control,  31 


370 


INDEX 


Culex   and  Anopheles,   differentia- 

•  tion,  28 

development,  25 

effect  upon  live  stock,  31 

lan-se,  24 

pathologic  importance,  26 

protection  against,  31 

pupse,  25 

range,  24 

relationship  to  filariasis,  26 

relationship  to  malaria,  26,  313,  320 

relationship  to  yellow  fever,  26,  29 
Multiceps  gaigeri,  181 

multiceps,  179,  194,  204,  206,  207 

serialis,  179 
Musca  domestica,  11,  37,  189 

vomitoria,  52 
Muscidffi,  20,  37 
MutuaHsm,  2,  7, 

example  of,  2,  7 
Myasis,  50 


Nagana,  45,  314,  330 

etiology,  45,  314,  330 

investigations  by  Bruce,  45,   314, 
330 

occurrence,  330 
Nemathehninthes,  155,  216,  222 
Nematoda,  217,  222, 
Nematode  worms,  parasitism  in  gen- 
eral, 219 

adaptabilitj'    to    changed  environ- 
ment, 221 

factors  influencing  injury  to  host, 
220 

host  limitations,  220 

infection,  219,  220 

treatment  in  general,  221 
Nematodirus  fiUcollis,  273 
Neosporidia,  336,  350 
Net  tick,  143 
Nodular  disease,  281 


Nodular  strongylosis  of  cattle,  285 

of  the  goat,  281 

of  the  hog,  287 
Nodular  strongylosis  of  the  sheep,  281 

development,  283 

importance,  284 

occurrence,  283 

post-mortem  appearance,  284 

sjTiiptoms,  284 

treatment,  285 
Notoedres,  101,  117 

var.  cati,  117,  118 

var.  cuniculi,  118 

parasitism  of,  103 
Notoedric  mange,  treatment  of,  120, 
123,  124 


Obhgate  parasites,  8 

Ocular  filariasis  of  the  horse,  245 

of  the  ox,  248 
(Esophagostomese,  280 
(Esophagostomiasis  of  cattle,  285 

of  the  goat,  281 

of  the  hog,  287 

of  the  sheep,  281 
CEsophagostomum,  255,  280 

columbianum,  281 

dentatiun,  287 

inflatum,  285 

radiatimi,  285 

subulatum,  287 

venulosum,  282 
(Estridse,  21,  53 
(Estrus  o\as,  62 
Optional  parasites,  8 
Organic  multiplication,  influences  re- 
stricting, 1 
Ornithobius  bucephalus,  86 
Ornithodorus  megnini,  140 
Ornithonomus  CA'-gni,  86 
Ostertagia  marshalli,  269 

ostertagi,  272 


INDEX 


371 


Otacariasis  of  the  cat,  118 
occurrence,  118 
treatment,  131 
Otacariasis  of  the  dog,  117 

occurrence,  117 

prognosis,  117 

sjTnptoms,  117 

treatment,  131 
Otacariasis  of  the  rabbit,  1 18 

course,  118 

sjinptoms,  119 

treatment,  I'M 
Otobius  megnini,  159 
Otodectes,  101,  103,  115,  117 

parasitism,  103 
Otodectes  cynotis,  115, 117 
Oviparous,  application  of  the  term, 

219 
0^^position,  18,  219 
Ovipositor,  18 
Ovo\aviparous,     application     of    the 

term,  219 
Ox  bot  flies,  57 

effect  of  bots,  62 

life  history,  58 

occurrence,  57 

treatment,  62 
Ox  warbles,  53,  57 
Oxyuriasis,  236 

effect,  236 

occurrence,  236 

treatment,  237 
Oxyuridffi,  222,  235 
OAjoirinse,  226 
Oxynris,  226 

curv'ula,  235 

equi,  235 

mastigodes,  235 


Parasites,  alternation  of  hosts  in,  5, 
Parasites,  determinate  transitory,  8 

determinate  erratic,  8 

erratic,  8 


fixed,  S 

heteroxenous,  8 

incidental,  8 

monoxenous,  8         * 

optional  occasional,  8 

permani  nt,  8 

stray,  8 
Parasites,     development    of     patho- 
genicity in,  315 
Parasites,  external,  9 

internal,  9 
Parasites,   factors    influencing  injury 
by,  10,  315 

age  of  host,  11 

location,  10,  315 

movements,  10 

nature  of  food,  10 

number  present,  10 
Parasites,  influence  upon  host,  10,  315 
Parasites,  systematic  position  of,  6 
Parasitic  diseases,  terms  used  in,  9 
Parasitism,  2,  3,  7,  315 

adaptation  to,  3,  4,  315 

degeneration  in,  3,  4 

factors  leading  to,  1,  6,  315 

forms  of,  7 

functions    involved   in    adaptation 
to,  3 

range  of,  3 

reproductive  function  in,  4 
Parasitism,  evolution  of,  315 
Parthenogenesis,  15,  322 
Pathogenic  Protozoa,  311,  324 

arthropods  as  carriers  of,  23,  315 
PedicuHdse,  21,  70 
Pediculosis  of  the  cat,  79 

control,  80 

occurrence,  79 

treatment,  81 
Pediculosis  of  cattle,  74 

control,  SO 

indications  of,  75 

location,  75 

treatment,  81 


372 


INDEX 


Pediculosis  of  the  dog,  78 

control,  80 

effect,  78 

location,  78   . 

treatment,  81 
Pediculosis  of  the  goat,  77 

control,  80 

effect,  77 

occurrence,  77 

treatment,  80 
Pediculosis  of  the  hog,  77 

control,  80 

effect,  77 

occurrence,  77 

treatment,  81 
Pediculosis  of  the  horse,  72 

control,  80 

indications  of,  73 

location,  73 

treatment,  80 
Pediculosis  of  mammals,  71 

complications,  71 

effect,  72 

indications  of,  72 

predisposing  factors,  71 

treatment,  80 
Pediculosis  of  man,  79 
Pediculosis  of  poultrj^,  82 

control,  88 

dust  bath  in,  88 

effect,  82 

indications  of,  82 

occurrence,  82 

parts  attacked,  82 

sodium    fluoride    in   treatment   of, 
88 

treatment,  88 
Pediculosis  of  the  sheep,  76 

control,  80 

occurrence,  77 

treatment,  80 
Pediculosis,  control  and  treatment,  80 
Pediculus  capitis,  79 

corporis,  79 


humanus,  79 
vestimenti,  79 
Permanent  parasites,  8 
Pharyngeal  filariasis  of  the  hog,  247 
Philopteridse,  21,  71 
Philopterus  cygni,  86 

icterodes,  84 
Phthiriasis,  71,  79 
Phthirius  inguinalis,  79 

pubis,  79 
Physocephalus  sexalatus,  252,  253 
Phytoparasites.  7 
Piroplasma  bigeminum,  313,  347 
Plasmodium,  313,  318 

falciparum,  318 

malarise,  318 

prsecox,  318 

yivax,  318 
Platyhelminthes,  155,  157 

classification  of,  155,  157 
Plerocercoid,  173,  195 
Polystomese,  156 
Polyzoa,  155,  159 
Pork  measles,  174,  195,  199 

degeneration  of  cyst,  202 

development,  202 

diagnosis,  202 

influence  of  temperature  upon  larvse, 
202 

locatin  and  appearance  of  cysts, 
201 

method  of  infection,  201 

occurrence,  200 

symptoms,  202 

vitality  of  larvse,  202 
Pork  tapeworm,  195,  199 
Poultry  mite,  98 

control,    9 

development,  99 

effect,  99 

habits,  98 

occurrence,  98 

reproduction,  99 
Predaceous  animals,  3,  9 


INDEX 


373 


Protozoa,  311 

carj'ozoic,  322 

coelozoic,  322 

colonization  of,  311 

cytozoic,  322 

differentiation  from  Metazoa,  311 

enterozoie,  322 

hematozoic,  322" 

investigations  as  to  patiiogenicity, 
313,  315 

investigations  as  to  pathogenicity  in 
the  United  States,  314 

natural  classification  of,  322 

parasitism,  313 

pathogenicity,  313,  315 

pathogenic  classificarion  of,  322 

specialization  in,  311 
Protozoa,  classification  of,  322 
Protozoa,  methods  of  reproduction  in. 
313,  318,  327,  329,  336,  337 

asexual  method,  318,  319,  337 

multiplicative  cycle,  318,  319,  337 

propagative  cycle,  318,  320,  337 

sexual  method,  318,  320,  337 

sporulation,  318,  319,  320,  336,  337 
Pseudopodia,  312,  324 
Psoroptes,  101,  102 

parasitism,  102 

species  of,  103 

varieties,  103 
Psoroptes  conmiunis,  103 

var.  bovis,  103,  113 

var.  cuniculi,  103,  118 

var.  equi,  103.  lOS 

var.  ovis,  103,  109 
Psoroptic  scabies  of  cattle.  113 

course,  113 

s\nnptoms,  113 

treatment,  120,  128 
Psoroptic  scabies  of  the  goat,  113 
Psoroptic  scabies  of  the  horse,  108 

lesions,  108 

transmission,  108 

treatment,  120.  129 


Psoroptic  .scabies  of  the  rabbit,  118 

course,  118 

sjinptoms,  119 

treatment,  120,  131 
Psoroptic  scabies  of  the  sheep,  109 

after-treatment,  128 

course,  110 

historical,  110 

lesions,  110 

prognosis,  110 

SNinptoms,  110 

treatment,  120,  124 
Pubic  louse,  79 
Pulex  irritans,  65 

serraticeps,  65 
Pulicida^,  21,  65 
Pulmonary  strongylosis  of  the  cat,  262 

.s\ini)toms,  262 
Pupation,  19 
Pyrosoma  bigeminum,  313 

R 

Red  bugs,  99 

Red  dysentery  of  cattle,  343 

Red  mange  of  the  dog,  104,  116 

Red-tailed  bot  fly,  57 

Remora,  2 

Reproduction,  oviparous,  18,  219 

ovoviparous,  18,219 

pupiparus,  4,  18 

viviparous,  18,  219 
Respirator^'  mite  of  fowl,  134 
Rhipicentor,  142 
Rhipicephalus,  142 
Rhizopoda,  322,  324 

reproduction  in,  324 
Rhvnchobdellidsp.  308 


Sarcocystis  bertrami,  351 
blanchardi,  351 
miescheriana,  351 
tenella,  351 


374 


INDEX 


Sarcophaga  sarraceiiise,  52 
Sarcoptes,  101 

parasitism,  102 

species  of,  102 

varieties,  102 
Sarcoptes  minor  var.  cati,  US 

minor  var.  cuniculi,  118 

mutans,  132 
Sarcoptes  scabiei,  102 

var.  boA-is,  114 

var.  canis,  115 

var.  equi,  104 

var.  o\as,  112 

var.  suis,  114 
Sacroptic  mange,  101,  102 

of  cattle,  114 

of  the  dog,  115 

of  the  goat,  113 

of  the  hog,  114 

of  the  horse,  104 

of  the  sheep,  112 
Sarcoptidse,  96,  101 
Sarcosporidia,  323,  336,  350 

development,  350 

muscles  commonl}^  invaded,  350 

parasitism,  350 

pathologic  importance,  351 

theorv^  as  to  source  and  mode  of 
infection,  351 

toxicity,  351 
Sarcosporidiosis,  350 

mode  of  infection,  352 
Sarcosporidiosis  of  cattle,  351 

of  the  horse,  351 

of  mice,  352 

of  the  pig,  351 
of  the  sheep,  351 
Scabies,  96 
Scab  mites,  94,  96 
Scaly  leg  of  poultry,  132 
Schistosoma  bovis,  16S 
Schistosomidse,  157 
Schizogony,  318,  319,  337 
Sclerostomiasis,  288 


Sclerostomum  edentatum,  289 
equinum,  288 
hypostomum,  287 
tetracanthum,  289 
vulgare,  289 
Scorpion,  94 
Screw  womi  fly,  50 
development,  50 
effect,  50 
occurrence,  50 
protection  from,  51 
reproduction,  50 
treatment,  51 
Sea  anemone  and  hermit  crab, 

mutualism  of,  2 
Septicemia  of  chicks,  345 
Setaria  labiato-papillosa,  244 
Sheep  bot  fly,  62 
effect  of  bots,  63 
life  liistory,  62 
occurrence,  62 
prevention,  64 
treatment,  64 
Sheep  measles,  174,  195,  203 
Sheep  measles,  muscular,  203 
control,  204 
derivation,  203 
development,  204 
economic  importance,  204 
occurrence,  203 
Sheep  measles,  \dsceral,  203 
control,  203 
development,  203 
method  of  infection,  203 
occurrence,  203 

relation  to  food  sanitation,  203 
sjTiiptoms,  203 
Sheep  staggers,  204 
Sheep  "tick,"  4,  47 
control,  48 
effect,  48 
life  history,  4,  47 
occurrence,  47 
treatment,  48 


INDEX 


375 


Simplicity,    primitive   and   degenera- 
tive, 3 
Simuliidte,  20,  31 
Simulium  pecuarmn,  32 
Siphonaptera,  21,  65 
Siphunculata,  21,  70 
Sleeping  sickness,  46,  314 
Southern  cattle  fever,  145,  313,  347 
Southern  cattle  tick,  144,  145,  347 
Spider,  94 
Spinose  ear  tick,  140 

development,  141 

effect,  141 

habits,  141 

occurrence,  141 
Spirocheta  gallinarum,  327 

marchouxi,  327 

theileri,  316 
Spirochetida,  315,  322,  327 

as  blood  parasites,  315,  316 

evolution  of  pathogenicity  in,  315 

pathogenicity,  315,  327 

transmission,  316 
Spirochetosis,  315,  327 

of  fowl,  327 
Spiroptera  megastoma,  245 

microstoma,  246 

sanguinolenta,  250 

scutata,  246 

sexalata,  252 

strongylina,  251 
Spirura,  227 
Spiruridse,  227 
Spirurinse,  227 

Splenic  fever  of  cattle,  145,  313,  347 
Sporogony,  318,  320,  337 
Sporozoa,  323, 336 

relationship    to    other   forms,    336 

reproduction  in,  318,  322,  336,  337 
Stable  fly,  39,  332 

control,  40 

effect,  40 

life  historj^,  39 

occurrence,  40 


protection  from,  41 

relation  to  infectious  diseases,   40 
332 
Staggers  of  sheep,  204 
Stegomya  calopus,  29 

fasciata,  29 
Stephanurus  dentatus,  295 
Sting,  insect,  18 
Stomach    wonns,     pasture     rotation 

in  eradication  of,  277 
Stomach  worms  of  cattle,  272 

of  the  goat,  268 

of  the  sheep,  268 
Stomoxys  calcitrans,  39,  315,  332 
Stray  parasites,  8 
Strongjdea,  280 
Strongj'les  of  the  resj^iratory  system, 

255,  256 
Strongj'lidcc,  223,  255 
]3arasitism  of,  255 
Strongj'linse.  223,  280 
Strongyloidca,  226 
Strongj'losis,  255 

bronchial,  256 

gastric,  268 

intestinal,  268,  280 

pulmonary,  256 

renal,  295,  296 

vascular,  289 
Strongj'losis,  bronchial  and  pulmonary 

of  cattle,  259 

of  the  goat,  256 

of  the  horse,  261 

of  the  pig,  260 

of  the  sheep,  256 
Strongylosis  of  the  intestines  of  the 

cat,  291 
Strongylosis  of  the  intestines  of  the 
dog,  291 

development,  292 

occurrence,  292 

post-mortem  appearance,  292 

sjTiiptoms,  292 

treatment,  293 


INDEX 


Strongylosis  of  the  intestines  of  the 
horse,  288 

development,  289 

post-mortem  appearance,  290 

sjTiiptoms,  290 

treatment,  291 
Strongylosis  of  the  large  intestine  of 

the  goat,  287 
Strongylosis  of  the  large  intestine  of 
the  sheep,  287 

occurrence,  288 
Strongylosis,  pulmonary  of  the  dog, 
261 

of  the  cat,  262 
Strongylosis,  tracheal,  of  poultry,  293 
Strongylus,  226,  255 

annatus,  288 

arnfieldi,  261 

capillaris,  258 

colubrifonnis,  271 

contortus,  268 

curticei,  268 

edentatus,  289 

equinus,  288 

filaria,  256 

fiUcollis,  273 

instabilis,  271 

micrurus,  259 

oncophora,  275 

ostertagi,  272 

paradoxus,  260 

pusillus,  262 

rufescens,  257 

vasorum,  261 

ventricosus,  268 

vulgaris,  255,  289 
Strongyl  worms,  importance  of,   255 

infestation,  conditions  favoring,  255 
Struggle  for  existence,  1 
Subcutaneous  mite  of  fowl,  134 
Summaries  on  development  of  Texas 

fever  tick,  149,  150 
Surra,  314,  315,  332 

course,  332 


flies  as  carriers  of,  314,  315,  332 

infection,  332 

occurrence,  332 

sjinptoms,  332 
Symbiosis,  2,  7 

phases  of,  2 
Symbiotes,  103 

communis,  103 
Sjaigameae,  281 
Syngamosis,  293 
Syngamus,  281,  294 

bronchialis,  293,  294 

trachealis,  293,  294 
Synopsis  of  tape  wo  mi  larvse,  194 
Synthetocaulus  abstrusus,  262 

capillaris,  258 

rufescens,  257 


Tabanida",  20,  35,  332 
Tabanus  atratus,  35 

lineola,  36 

striatus,  332 
Table    of    principal    tapeworais    and 

larvae,  173 
T»nia,  173 
Taenia  alba,  176 

cesticillus,  190 

coenurus,  179 

crassicoUis,  184 

cucumerina,  178 

echinobothrida,  191 

echinococcus,  181,  210 

expansa,  176 

fimbriata,  174,  176,  177 

hydatigena,  178,  195,  203 

mamillana,  175 

marginata,  178 

mediocanellata,  195 

ovis,  204 

perfoliata,  174 

plicata,  175 

proglottina,  191 


INDEX 


377 


saginata,  170,  174,  195 

serialis,  179 

serrata,  179 

solium,  174,  195 

tsenisefomiis,  184 

tetragona,  190 
Ta^niasis,  172,  174 

prevention,  187 

treatment  in  general,  186 
Tffniida",  20,  159,  170 

life  history  of,  169,  171 
Tail  scab  of  cattle,  113 
Tapeworm  larvae,  173,  174,  194 

synopsis  of,  194 
Tapeworms,  5,  169 

classification  of,  159,  173 

cystic  fonns,  173,  194 

degeneration  of,  5,  172 

parasitism  of,  5,  172 
Tapewonns  of  the  cat,  184 

occurrence,  184 

symptoms,  184 

treatment,  188 
Tapewonns  of  cattle,  176 

occurrence,  177 

symptoms,  177 

treatment,  188 
Tapewonns  of  chickens,  189 

control,  192 

diagnosis,  192 

investigations  as  to,  189 

occurrence,  189,  191 

sjTnptoms,  191 

treatment,  192 
Tapewonns  of  the  dog,  178 

diagnosis,  183 

occurrence,  181 

pathogenesis,  182 

prevention,  187 

relation  to  human  infection,  183 

s\inptoms,  181 

treatment,  186 
Tapewonns  of  the  horse,  174 

occurrence,  175 


symptoms,  175 

treatment,  188 
Tapewonns  of  the  rabbit,  185 

diagnosis,  185 

occurrence,  185 
Tapewonns  of  the  sheep,  176 

occurrence,  177 

symptoms,  177 

treatment,  188 
Telosporidia,  336 
Tetrameres  fissispina,  254 
Texas  fever,  11,  145,  313,  347 

acute  type,  349 

chronic  tjije,  349 

development  of  the  piroplasma,  348 

distribution,  348 

infecting  organism  of,  347 

influence  of  climate  upon,  349 

occurrence,  348 

l)eriod   from   exjiosure   to   develop- 
ment, 348 

prevention,  350 

relationship  of  the  tick  to  transmis- 
sion, 145,  314,  347 

sjinptoms,  349 

treatment,  350 
Texas  fever  tick,  11,  144,  145,  314,  347 

losses  occasioned  by,  151 

progress  in  eradication  of,  152 

publications  relative  to,  145 
Texas  fever  tick,  life  history  of,  148, 347 

adult  period,  150 

hatching  period,  148 

incubation  period,  148 

larval  period,  150 

longevity  period,  149 

nonparasitic  development,  148 

njinphal  period,  150 

oviposit  ion  period,  148 

parasitic  development,  149 

preoviposition  jieriod,  148 

summary    of   nonparasitic   periods, 
149 

summary  of  parasitic  jieriotls,  150 


378 


INDEX 


Thorn-headed  womi,  306 
Thorn-headed  womi  of  the  hog,  303 

life  history,  306 

occurrence,  306 

pathogenesis,  306 

symptoms,  306 

treatment,  307 
Thj^sanosoma    actinioides,    174,    176, 

177 
Tick  fever,  365,  145,  313,  347 
Ticks,  136 

classification  of,  136 

stages  in  development  of,  139,  145 

structure  of,  136 
Tick,    Texas    fever,    144,    145,    314, 

347 
Toxascaris  limbata,  238 

marginata,  238 
Toxins,  parasitic,  11,  174,  220 
Tracheal  injections,  265 
Tracheal  strongjdosis  of  fowl,  293 

development,  294 

lesions,  294 

occurrence,  294 

prevention,  295 

symptoms,  294 

treatment,  295 
Transmigration,  8 
Trematoda,  156,  157 
Trichina  spiraHs,  220,  299,  301 
Trichinella,  225 
Trichinella  spiralis,  220,  299,  301 

degeneration  of  cyst  of,  303 

development  of  cyst  of,  302 

life  liistory,  302 

location  of  cysts  of,  303 

migration,  220,  302 
Trichinellidse,  224,  299 
Trichinellinffi,  225 
Tricliinelloidea,  225 
Trichinosis,  220,  301 

intestinal,  302 

method  of  infection,  302,  304 

muscular,  302 


occurrence,  301,  304 

prophj-laxis,  305 

symptoms  in  the  hog,  304 

treatment,  305 
Tricliinosis  in  man,  304. 
Trichocephalus  affinis,  299 

crenatus,  299 

depressiusculus,  300 
Trichodectes  clmiax,  77 

equi,  73 

latus,  78 

panmipilosus,  73 

pilosus,  73 

scalaris,  75 

sphserocephalus,  76 

subrostratus,  79 
Trichostrongylidae,  226 
Trichostrongylinse,  223,  268 
Trichostrongjdus,  226 

instabilis,  271 
Trichurinse,  225 
Trichuris,  225 

crenatus,  299 

depressiusculus,  300 

o\as,  299 
Trinoton  lituratum,  86 

luridum,  84 
Trinotum  lituratum,  86 

luridum,  84 
Triodontophorus,  281 
Trombidiidffi,  96,  99 
Trombidium  holosericeum,  100 
Tropisurus  fissispinus,  254 
Trypanoplasma,  328 
Trypanosoma,  328 

americanum,  336 

brucei,  314,  330 

equinum,  332 

equiperdum,  333 

evansi,  C14,  332 

gambiense,  314 

le^visi,  314 

theileri,  329 
Tiypanosomatida,  322,  328 


INDEX 


379 


Trypanosomes,  314,  32S 

classification  of,  322,  32S 

morphology  of,  328,  329 

parasitism  of,  314,  329 

reproduction,  329 

transmission,  314,  329 

transmission  by  flies,  45,  314,  329 
Trypanosomes,    flies    as    carriers    of, 
45,  314,  329 

leeches  as  carriers  of,  314 

lice  as  carriers  of,  314 

mosquitoes  as  carriers  of,  314 
Trj'-panosomiasis,  11,  45,  314,  328 

human,  46,  314 

investigations  by  Bruce,  45,  314,  330 
Tsetse  flies,  44,  314,  330 

control,  43 

method  of  reproduction,  44 

relationship  to  trypanosomiasis,  45, 
314,  330 
Tsetse  fly  disease,  44,  314,  330 

investigations   by   Bruce,   44,   314, 
330 
Tunicata,  3 
Tumsick,  204 
Typhoid  fever,  11, 


U 


Uncinaria,  281 
Uncinariasis,  291 


Uncinaria  canina,  291 
cernua,  293 
radiata,  293 
stenocephala,  292 
trigonocephala,  291 

V 

Vermes,  155 

Vermicides,  use  and  action  of,  121,  186 
Vermifuges,  use  and  action  of,  121, 186 
Verminous  bronchitis  and  pneumonia 
of  cattle,  259 

of  children,  231 

of  the  goat,  256 

of  the  horse,  261 

of  the  pig,  231,  260 

of  the  sheep,  256 
Vi\'iparous,  application  of  the  term, 
219 

W 

Warble  flies,  53,  57 
White  diarrhea  of  chicks,  345 
Wood  tick,  143 
Wo  mis,  155 

classification  of,  155,  157,  173 


Zooparasites,  8 


Printed  in  the  United  States  of  America 


JUL  0  1  2000 
MAK  1  8  ZM/ 


